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CHEMISTRY 


IN  ITS  APPLICATIONS 


AGRICULTURE  AND  PHYSIOLOGY. 


BY 

JUSTUS  LIEBIG,   M.D.,   Ph.D.,   F.R.S.,  M.R.I.A., 

PROFKSSOR    OK    CHEMISTRY   IN  THE    UNIVERSITY    OF    GIKSSEN,    ETC.,    ETC 


EDITED  FROM  THE  MANUSCRIPT  OF  THE  AUTHOR, 

BY  LYOX  PLAYFAIR,  Ph.D.,  F.G.S., 

HONORARY  MEMBER  OF  AND  CONSULTING  CHEMIST  TO  THE  ROYAL  AORICULTCRAL 
SOCIETY  OF  ENGLAND, 

AND  WILLIAM  GREGORY,  M.D.,  F.R.S.E., 

rROFCSSOR  OF  CHEMISTRY  IN  THE  UNIVERSITY  OF  EDINBUROB. 
'       '  ...         .  »       •  » • 


FROM  TUt  FOUfe^^lI  LONDON   EDITION, 


REVISED    AND    ENLARGED. 


NEW    YORK: 
JOHN    WILEY,    167    BROADWAY. 

1852. 


\ 


€" 


MAIN  LIBRARY  AGRIC.  DEFr. 


C  .    *     •    ,«     c 


ADVERTISEMENT 
TO    THE    FOURTH    EDITION. 


The  present  edition  is  enriched  with  a  large  number  of  recent 
analyses  of  manures ;  and  especially  of  the  ashes  of  plants, 
which  will  be  found  in  the  Appendix  to  Part  I.  The  greater 
number  of  these  analyses  have  been  made  under  the  eye  of  the 
Author  in  the  Laboratory  at  Giessen,  and  with  the  aid  of  the 
most  improved  methods. 

At  the  request  of  Professor  Liebig  I  assisted  in  the  preparation 
of  the  last  edition  of  this  Work,  the  various  engagements  of  Dr. 
Play  fair  having  so  fully  occupied  his  time  as  to  preclude  him 
from  giving  the  requisite  attention  to  it.  The  same  causes  have 
led  to  my  undertaking  the  entire  revision  of  the  present  edition. 

WILLIAM  GREGORY. 
Umitbrsity  or  EoiNBrReH, 
March,  1847. 


|yi66978 


AUTHOR'S    PREFACE 
TO    THE  THIRD  EDITION. 


Majvy  views  and  principles  which  I  had  endeavored  to  de. 'elope 
in  reference  to  nutrition,  and  especially  to  the  cultivation  of 
vegetables,  were  strongly  opposed,  immediately  on  the  appeaV- 
ance  of  the  first  edition  of  this  Work.  I  could  not,  however, 
resolve  to  make  any  material  change  in  the  immediately  succeed- 
ing edition,  because  I  did  not  consider  the  scientific  investigation 
of  the  important  questions  at  issue  as  completed,  and  because  I 
thought  that  I  ought  to  trust  the  decision  of  them  to  experience 
alone. 

Many  of  the  objections  raised  were  founded  upon  a  want  of 
mutual  understanding  ;  others  related  to  positions  and  assertions 
having  no  connexion  with  the  peculiar  object  of  the  book.  I 
have  set  these  aside  by  the  omission  of  all  passages  thus  called 
in  question. 

In  the  three  years  which  have  elapsed  between  this  edition  and 
the  first,  I  have  not  neglected  any  opportunity  of  subjecting  to  a 
rigorous  and  careful  examination  the  principles  which  I  had 
developed  of  the  nutritive  properties  of  plants,  and  their  applica- 
tion to  agriculture.  I  have  endeavored  to  make  myself  acquainted 
with  the  condition  of  practical  farming,  and  with  what  it  requires, 
by  a  journey  through  the  agricultural  districts  of  England  and 
Scotland  ;  and  during  this  interval  a  long  series  of  experiments 


riii  PREFACE. 


were  carried  on  in  the  Laboratory  of  this  place,  with  the  sole 
object  of  giving  a  firmer  basis  to  my  exposition  of  the  causes  of 
the  advantageous  results  attending  the  practice  of  rotation  of 
crops,  and  also  of  effectually  banishing  all  doubts  concerning 
their  accuracy. 

In  my  "Chemistry  in  its  applications  to  Physiology  and 
Pathology,"  I  have  subjected  the  process  of  nutrition  of  the 
animal  organism  to  a  stricter  investigation ;  and  I  am  now,  for 
the  first  lime  since  the  completion  of  these  labors,  in  a  situation 
to  give  a  simple  and  determinate  expression  to  my  view  of  the 
origin  of  animal  excrements,  and  of  the  cause  of  their  beneficial 
effects  on  the  growth  of  all  vegetables. 

Now  that  the  conditions  which  render  the  soil  productive  and 
capable  of  affording  support  to  plants,  are  ascertained,  it  cannot 
well  be  denied  that  from  Chemistry  done  further  progress  in 
Agriculture  is  to  be  expected. 

Every  unprejudiced  person  will,  I  trust,  be  finally  convinced 
by  this  third  edition,  that  I  have  earnestly  endeavored  to  perfect 
my  views,  and  have  striven,  with  the  best  intentions,  to  ascertaiii 
truth  and  obviate  error. 

JUSTUS  LIEBIG. 

GlESSKN, 

JlMfutl,  1843. 


J  )u  «ia«4«Hli  4|*«i*«  4>'  i*^';^  ..■'i-^iik,  kHi^. 


THE    BRITISH    ASSOCIATIOJI 


ADVANCEMENT  OF  SCIENCE. 


One  of  the  most  remarkable  features  of  modern  times  is  the 
combination  of  large  numbers  of  individuals  representing  the 
whole  intelligence  of  nations,  for  the  express  purpose  of  ad- 
vancing science  by  their  united  efforts,  of  learning  its  progress, 
and  of  communicating  new  discoveries.  The  formation  of  such 
associations,  is,  in  itself,  an  evidence  that  they  were  needed. 

It  is  not  every  one  who  is  called  by  his  situation  in  life  to 
assist  in  extending  the  bounds  of  science  ;  but  all  mankind  have 
a  claim  to  the  blessings  and  benefits  which  accrue  from  its 
earnest  cultivation.  The  foundation  of  scientific  institutions  is 
an  acknowledgment  of  these  benefits,  and  this  acknowledgment 
proceeding  from  whole  nations  may  be  considered  the  triumph  of 
mind  over  empiricism. 

Innumerable  are  the  aids  afforded  to  the  means  of  life,  to 
manufactures,  and  to  commerce,  by  the  truths  which  assiduous 
and  active  inquirers  have  discovered  and  rendered  capable  of 
practical  application.  But  it  is  not  the  mere  practical  utility  of 
these  truths  which  is  of  importance.      Their   influence    upon 


DEDICATION. 


mental  culture  is  most  beneficial ;  and  the  new  views  acquired 
by  the  knowledge  of  them  enable  the  mind  to  recognise,  in  the 
phenomena  of  nature,  proofs  of  an  Infinite  Wisdom,  for  the 
unfathomable  profundity  of  which  language  has  no  expression. 

At  one  of  the  meetings  of  the  Chemical  Section  of  the  "  British 
Association  for  the  Advancement  of  Science,"  the  honorable  task 
of  preparing  a  Report  upon  the  state  of  Organic  Chemistry  was 
imposed  upon  me.  In  the  present  work  I  present  the  Association 
with  a  part  of  this  report. 

I  have  endeavored  to  develope,  in  a  manner  correspondent  to 
the  present  state  of  science,  the  fundamental  principles  of 
Chemistry  in  general,  and  the  laws  of  Organic  Chemistry  in 
particular,  in  their  applications  to  Agriculture  and  Physiology  ; 
to  the  causes  of  fermentation,  decay,  and  putrefaction  ;  to  the' 
vinous  and  acetous  fermentations,  and  to  nitrification.  The  con- 
version of  woody  fibre  into  wood  and  mineral-coal,  the  nature  of 
poisons,  contagions,  and  miasms,  and  the  causes  of  their  action 
on  the  living  organism,  have  been  elucidated  in  their  chemical 
relations. 

I  shall  be  happy  if  I  succeed  in  attracting  the  attention  of  men 
of  science  to  subjects  which  so  well  merit  to  engage  their  talents 
and  energies.  Perfect  Agriculture  is  the  true  foundation  of  all 
trade  and  industry — it  is  the  foundation  of  the  riches  of  states. 
But  a  rational  system  of  Agriculture  cannot  be  formed  without 
the  application  of  scientific  principles  ;  for  such  a  system  must 
be  based  on  an  exact  acquaintance  with  the  means  of  nutrition 
of  vegetables,  and  with  the  influence  of  soils  and  actions  of 
manure  upon  them.  This  knowledge  we  must  seek  from  Che- 
mistry, which  teaches  the  modo  of  investigating  the  composition 
and  of  studying  the  characters  of  the  different  substances  from 
which  plants  derive  their  nourishment. 

The  chemical  forces  play  a  part  in  all  the  processes  of  the  living 
animal  organism  ;  and  a  number  of  transformations  and  changes 


DEDICATION. 


in  the  living  body  are  exclusively  dependent  on  their  influence. 
The  diseases  incident  to  the  period  of  growth  of  man,  contagion, 
and  contagious  matters,  have  their  analogues  in  many  chemical 
processes.  The  investigation  of  the  chemical  connexion  subsist- 
ing between  those  actions  proceeding  in  the  living  body,  and  the 
transformations  presented  by  chemical  compounds,  has  also  been 
a  subject  of  my  inquiries.  A  perfect  exhaustion  of  this  subject, 
so  highly  important  to  medicine,  cannot  be  expected  without  the 
co-operation  of  physiologists.  Hence  I  have  merely  brought 
forward  the  purely  chemical  part  of  the  inquiry,  and  hope  tc 
attract  attention  to  the  subject. 

Since  the  time  of  the  immortal  author  of  the  "  Agricultural 
Chemistry,"  no  chemist  has  occupied  himself  in  studying  the 
applications  of  chemical  principles  to  the  growth  of  vegetables, 
and  to  organic  processes.  I  have  endeavored  to  follow  the  path 
marked  out  by  Sir  Humphry  Davy,  who  based  his  conclusions 
only  on  that  which  was  capable  of  inquiry  and  proof.  This  is 
the  path  of  true  philosophical  inquiry,  which  promises  to  lead  us 
to  truth — the  proper  object  of  our  research. 

In  presenting  this  Report  to  the  British  Association  I  feel 
myself  bound  to  convey  my  sincere  thanks  to  Dr.  Lyon  Playfair, 
of  St.  Andrew's,  for  the  active  assistance  which  has  been  afforded 
me  in  its  preparation  by  that  intelligent  young  chemist  during  his 
residence  in  Giessen.  I  cannot  suppress  the  wish  that  he  may 
succeed  in  being  as  useful,  by  his  profound  and  well-grounded 
knowledge  of  chemistry,  as  his  talents  promise. 

JUSTUS   LIEBIO. 

Giessen, 
September  1,  1840. 


CONTENTS. 


rios 

Ojiject  or  THE  Work            ..-.----.  1 

PART  THE  FIRST. 

ON  THE  CHEMICAL  PROCESSES  IX  THE  NUTRITION  OF  VEGE'IABLIM. 

CHAPTER 

I. — The  Constituent  Elements  of  Plants 3 

II. — The  Origin  and  Assiniilntion  of  Carbon        .         -         -         -  5 

III. — On  the  Origin  and  Action  of  Hunuis     -----  28 

IV.^ — On  the  Assimilation  of  Hydrogen 35 

V. — On  the  Origin  and  Assimilation  of  Nitrogen           -         -         -  40 

Vr.— On  the  Source  of  Sulphur 58 

VII. — Of  the  Inorganic  Constituents  of  Plants       -         -         -         -  64 

VIII. — On  the  Formation  of  Arable  Land        -----  81 

IX.— The  Art  of  Culture 93 

X.— rOn  Fallow .         .  103 

XI.— On  the  Rotation  of  Crops 133 

XII. — On  Manure          -         -                  16G 

XIII.— Retrospective  view  of  the  Preceding  Theories        -         -         -  186 

Supplementary  Chapters. — The  Sources  of  Ammonia          -         -  205 

Is  Nitric  Acid  food  for  plants  ? 214 

Does  the  Nitrogen  of  the  Air  take  part  in  Vegetation  ?     -  223 

Giant  Sea-weed      --------  225 

Appendix  to  Part  I. -  227 

Experiments  of  Wiegmann  and  Polstorf           -         -         -  227 

and  Analyses  of  Boussingault       ...  231 

Analyses  of  Hertwig        -         - 238 

Fresenius     ----.-.  239 

Berthier 240 

De  Saussure         ------  242 

Recent  Analyses  of  the  Ashes  of  Plants  -         -         .      247,  254 

Analyses  of  Animal  Excrements    -----  255 

Urine           ---.-.-.  256 

Guano          -         -         -         -         -         .        -  258 

Marl -  264 

Ammonia  in  the  Soil 264 


CONTENTS. 


PART  THE  SECOND. 

ON  THE  CHEMICAL  PROCESSES  OP  FERMENTATION,  DECAY,  AND 
PUTREFACTION. 

CHAPTER  PA.OI 

I. — Chemical  Transformations -  265 

II. — On  the  Causes  which  effect  Fermentation,  Decuy,  and  Putre- 
faction      26S 

III. — Fermentation  and  Putrefaction     ------  27ij 

IV, — On  the  Transformation  of  Bodies  which  do  not  contain  Nitro- 
gen as  a  Constituent,  and  of  those  in  which  it  is  present    -  280 
On  the  Transformation  of  Bodies  containinj^  Nitroj^en        -  2S2 

V. — Fermentation  of  Sugar -         -  287 

Yeast  or  Ferment ---  289 

VI. — Eremacausis,  or  Decay -         -  295 

VII. — Eremacausis,  or    Decay   of    Bodies   destitute   of  Nitrogen : 

Formation  of  Acetic  Acid          ------  302 

VIII. — Eremacausis   of    Substances  containing  Nitroge'n. — Nitrifi- 
cation     ----------  307 

IX. — On  Vinous  Fermentation  : — Wine  and  Beer          -         -         -  311 
X. — On  Fermentation  ascribed  to  the  Growth  of  Fungi  and  of 

Infusoria 328 

XL— Decay  of  Woody  Fibre -         -  338 

XII.— Vegetable  Mould 344 

XIII.— On  the  Mouldering  of  Bodies : — Paper,  Brown  Coal,  and  Mine- 
ral Coal 340 

XIV. — On  Poisons,  Contagions,  and  Miastis 354 

Appendix  to  Part  II. 391 

Index 393 


ORGANIC  CHEMISTRY 


IN   ITS    APPLICATION   TO 


VEGETABLE  PHYSIOLOGY  AND  AGRICULTURE. 


The  object  of  Organic  Chemistry  is  to  discover  the  chemical 
conditions  essential  to  the  life  and  perfect  development  of  animals 
and  vegetables,  and  generally  to  investigate  all  those  processes  of 
organic  nature  which  are  due  to  the  operation  of  chemical  laws. 
Now,  the  continued  existence  of  all  living  beings  is  dependent  on 
the  reception  by  them  of  certain  substances,  which  are  applied 
to  the  nutrition  of  their  frame.  An  inquiry,  therefore,  into  the 
conditions  on  which  the  life  and  growth  of  living  beings  depend, 
involves  the  study  of  those  nutritive  substances,  as  well  as  the 
investigation  of  the  sources  whence  they  are  derived,  and  of  the 
changes  undergone  by  them  in  the  process  of  assimilation. 

A  beautiful  connexion  subsists  between  the  organic  and  inor- 
ganic kingdoms  of  nature.  Inorganic  matter  affords  food  to 
plants; ;  and  they,  on  the  other  hand,  yield  the  means  of  subsist- 
ence to  animals.  The  conditions  necessaiy  for  animal  and  vege- 
table nutrition  arc  essentially  different.  An  animal  requires  for 
its  development,  and  for  the  sustenance  of  its  vital  functions,  a 
certain  class  of  substances  which  can  be  generated  only  by 
organic  beings  possessed  of  life.  Although  many  animals  are 
entirely  carnivorous,  yet  their  primary  nutriment  must  be  derived 
from  plants  ;  for  the  animals  upon  •^which  they  subsist  receive 
their  nourishment  from  vegetable  matter.     Plants,  on  the  other 

PART  I.  2 


SUBJECT  OF  THE  WORK 


hand,  find  new  nutritive  material  only  in  inorganic  substances. 
Hence,  one  great  end  of'  vegetable  life  is  to  generate  matter 
adapted  for  the  nutrition  of  animals,  out  of  inorganic  substances, 
which  are  not  fitted  for  this  purpose.  Now,  the  purport  of  this 
work  is,  to  elucidate  the  chemical  processes  engaged  in  the 
nutrition  of  vegetables,  as  well  as  the  changjes  which  they  undergo 
after  death. 

The  first  part  of  it  will  be  devoted  to  the  examination  of  the 
matters  which  supply  the  nutriment  of  plants,  and  of  the  changes 
which  these  matters  undergo  in  the  living  organism.  The  che- 
mical compounds  which  aiford  to  plants  their  principal  constitu- 
ents, viz.,  carbon,  nitrogen,  hydrogen,  oxygen,  and  sulphur,  will 
here  come  under  consideration,  as  well  as  the  relations  in  which 
the  vital  functions  of  vegetables  stand  to  those  of  the  animal 
economy  and  to  other  phenomena  of  nature. 

The  second  part  of  the  work  will  treat  of  the  peculiar  processes 
usually  described  as  fermentation,  putrefaction,  and  decay.  By 
the  action  of  these  processes,  the  complete  destruction  of  plants 
and  animals  after  death  is  effected.  Flence  the  changes  under- 
gone by  the  elements  of  organic  tissues  in  their  conversion  into 
inorganic  compounds,  as  well  as  the  cause  by  which  these  changes 
are  determined,  will  become  matter  of  inquiry. 


PART  I. 


THE  CHEMICAL  PROCESSES  IN  THE  NUTRITION  OP 
VEGETABLES. 


CHAPTER  I. 

The  Constituent  Elements  of  Plants. 


Carbon  and  hydrogen  invariably  occur  in  all  parts  of  plants. 
They  form  constituents  of  all  their  organs,  and  are  essential  to 
their  existence.  v 

The  substances  which  constitute  the  principal  mass  of  every 
vegetable  are  compounds  of  carbon  with  oxygen  and  hydrogen, 
in  the  proper  relative  proportions  for  forming  water.  Woody 
fibre,  starch,  sugar,  and  gum,  for  example,  are  such  compounds 
of  carbon  with  the  elements  of  water.  In  another  class  of  sub- 
stances containing  carbon  as  an  element,  oxygen  and  hydrogen 
are  again  present ;  but  the  proportion  of  oxygen  is  greater  than 
would  be  required  for  producing  water  by  union  with  the  hydro- 
gen. The  numerous  organic  acids  met  with  in  plants,  belong, 
with  few  exceptions,  to  this  class. 

A  third  class  of  vegetable  compounds  contains  carbon  and  hy- 
drogen, but  no  oxygen,  or  less  of  that  element  than  would  be 
required  to  convert  all  the  hydrogen  into  water.  These  may  be 
regarded  as  compounds  of  carbon  with  the  elements  of  water,  and 
an  excess  of  hydrogen.  Such  are  the  volatile  and  fixed  oils, 
wax,  and  the  resins.     Many  of  them  have  acid  characters. 

The  juices  of  all  vegetables  contain  organic  acids,  generally 
combined  with  the  inorganic  bases,  or  metallic  oxides ;  for  metal- 
lic oxides  exist  in  every  plant,  and  may  be  detected  in  its  ashes 
after  incineration. 


THE  CONSTITUENT  ELEMENTS  Ox^  PLANTS. 


Nitrogen  is  found  in  plants  in  the  form  of  vegetable  albumen 
and  gluten  ;  it  is  also  a  constituent  of  some  of  the  acids,  and  of 
what  are  termed  the  "  indifferent  substances  "  of  plants,  as  well 
as  of  those  peculiar  vegetable  compounds  called  "  organic 
bases,"  which  possess  all  the  properties  of  metallic  oxides.  The 
seeds  also  of  all  plants  contain  nitrogenous  compounds. 

Estimated  by  its   proportional  weight,  nitrogen  forms  only  a 

small  part  of  plants  ;  but  it  is  never  entirely  absent  from  any 

•pjiKtof  theip..'  iljv^ni  \\hen  it  does  not  absolutely  enter  into  the 

c€)rt>positi(5n "bf  a' jiarticular  part  or  organ,  it  is  always  to  be  found 

ill  the  "fluids  -v/l^ich  p.t\rv'ade  it. 

'*  •'jCh6 ''niti-ogehcyU-i^  com[Jounds  thus  invariably  present  in  the 
seeds  and  juices  of  plants  contain  a  certain  quantity  of  sulphur. 
When  the  juices,  seeds,  or  organs  of  particular  kinds  of  plants 
are  subjected  to  distillation  along  with  water,  peculiar  oily  sub- 
stances pass  over.  These  are  volatile,  and  are  characterized  by 
their  large  proportion,  both  of  sulphur  and  of  nitrogen.  The 
volatile  oils  of  the  horse-radish  and  of  mustard  are  examples  of 
this  class  of  bodies. 

From  the  remarks  now  made,  it  is  obvious  that  there  are  two 
great  classes  into  which  all  vegetable  products  may  be  arranged. 
The  first  of  these  contains  nitrogen  ;  in  the  last  this  element  is 
absent.  The  compounds  destitute  of  nitrogen  may  be  divided 
into  those  in  which  oxygen  forms  a  constituent  (starch,  lignine, 
<&c.),  and  those  into  which  it  does  not  enter  (oils  of  turpentine 
and  lemon,  &c.).  The  nitrogenous  compounds  may,  in  like 
manner,  be  divided  into  three  smaller  classes.  The  first  of  these 
is  distinguished  by  containing  both  sulphur  and  oxygen  (in  all 
seeds)  ;  the  second  contains  sulphur,  but  is  devoid  of  oxygen  (as 
oil  of  mustard) ;  while  the  third  is  composed  of  bodies  from 
which  sulphur  is  entirely  absent  (organic  bases). 

It  follows  from  the  facts  thus  far  detailed,  that  the  development 
of  a  plant  requires  the  presence,  first,  of  substances  containing 
carbon,  nitrogen,  and  sulphur,  and  capable  of  yielding  these 
elements  to  the  growing  organism ;  secondly,  of  water  and  its 
elements ;  and  lastly,  of  a  soil  to  furnish  the  inorganic  matters 
which  are  likewise  essential  to  vegetable  life. 


PROPERTIES  OF  HUMUS. 


CHAPTER  II. 
THE  ORIGIN  AND  ASSIMILATION  OF  CARBON. 

Composition  of  Humus. 

Some  virgin  soils,  such  as  those  of  America,  contain  vegetable 
matter  in  large  proportion  ;  and  as  these  have  been  found  emi- 
nently adapted  for  the  cultivation  of  most  plants,  the  organic 
matter  contained  in  them  has  naturally  been  recognised  as  the 
cause  of  their  fertility.*  To  this  matter,  the  term  "  vegetable 
mould  "  or  humus  has  been  applied.  Indeed,  this  peculiar  sub- 
stance appears  to  play  such  an  important  part  in  the  phenomena 
of  vegetation,  that  vej^etable  physiologists  have  been  induced  to 
ascribe  the  fertility  of  every  soil  to  its  presence.  It  is  believed 
by  many  to  be  the  principal  nutriment  of  plants,  and  is  supposed 
to  be  extracted  by  them  from  the  soil  in  which  they  grow.  It 
is  a  product  of  the  putrefaction  and  decay  of  vegetable  matter. 

The  humus,  to  which  allusion  has  been  made,  is  described  by 
chemists  as  a  brown  substance  easily  soluble  in  alkalies,  but  only 
slightly  so  in  water,  and  produced  during  the  decomposition  of 
vegetable  matters  by  the  action  of  acids  or  alkalies.  It  has, 
however,  received  various  names,  according  to  the  different  ex- 
ternal characters  and  chemical  properties  which  it  presents. 
Thus,  ulmin,  humic  acid,  coal  of  humus,  and  humin,  are  names 

*  When  the  weight  of  the  soluble  parts  of  this  vegetable  matter  is  com- 
pared with  that  of  the  plants  growing  upon  t,  it  is  seen  that  only  a  very 
small  part  of  their  substance  could  have  been  procured  through  its  agency. 
This  is  the  case  even  in  the  most  fertile  soils. — (Saussure,  Richerehe* 
$ur  la  VigHation. 


OF  THE  ASSIMILATION  OF  CARBON. 


applied  to  modifications  of  humus.  They  are  obtained  by  treat- 
ing peat,  woody  fibre,  soot,  or  brown  coal,  with  alkalies ;  by  de- 
composing sugar,  starch,  or  sugar  of  milk  by  means  of  acids;  or 
by  exposing  alkaline  solutions  of  tannic  and  gallic  acids  to  the 
action  of  the  air. 

The  modifications  of  humus  which  are  soluble  in  alkalies,  are 
called  humic  acid;  while  those  which  are  insoluble  have  received 
the  designations  of  humin  and  coal  of  humus. 

The  names  given  to  these  substances  might  cause  it  to  be  sup- 
posed that  their  composition  is  identical.  But  a  more  erroneous 
notion  could  not  be  entertained ;  since  even  sugar,  acetic  acid, 
and  resin,  do  not  differ  more  widely  in  the  proportions  of  their 
constituent  elements,  than  do  the  various  modifications  of  humus. 

HuMic  ACID  formed  by  the  action  of  hydrate  of  potash  upon 
sawdust  contains,  according  to  the  accurate  analysis  of  Peligot, 
72  per  cent,  of  carbon,  while  the  humic  acid  obtained  from  turf 
and  brown  coal  contains,  according  to  Sprengel,  only  58  per 
cent.  ;  that  produced  by  the  action  of  dilute  sulphuric  acid  upon 
sugar,  57  per  cent,  according  to  Malaguti ;  and  that,  lastly, 
which  is  obtained  from  sugar  or  from  starch,  by  means  of  muri- 
atic  acid,  according  to  the  analysis  of  Stein,  64  per  cent.  Mala- 
guti states,  moreover,  that  humic  acid  contains  an  equal  number 
of  equivalents  of  oxygen  and  hydrogen,  that  is  to  say,  that  these 
elements  exist  in  it  in  the  proportions  for  forming  water  ;  while, 
according  to  Sprengel,  the  oxygen  is  in  excess  ;  and  Peligot  esti- 
mates the  quantity  of  hydrogen  at  14  equivalents,  and  the  oxygen 
at  only  6  equivalents,  making  the  deficiency  of  oxygen  as  great 
as  8  equivalents.  Mulder  and  Herrmann  have  shown  that  de- 
cayed willow- wood,  peat,  or  vegetable  mould,  after  being  treat- 
ed with  water  and  alcohol,  leave  a  solid  brown  substance,  which 
yields  to  alkalies  a  peculiar  humic  acid.  This  humic  acid  con- 
sists of  carbon  and  the  elements  of  water.  But  besides  these 
usual  constituents,  it  contains  a  certain  quantity  of  ammonia,  in 
a  state  of  chemical  combination. 

It  is  quite  evident,  therefore,  that  chemists  have  been  in  the 
habit  of  designating  by  the  names  of  humic  acid  or  humin,  all 
the  brown  or  black-colored  products  of  the  decomposition  of 
organic  bodies,  according  as  they  were  soluble  or  insoluble  in 


PROPERTIES  OF  HUMUS. 


alkalies ;  although  in  their  composition  and  mode  of  origin  the 
substances  thus  confounded  might  be  in  no  way  allied. 

Not  the  slightest  ground  exists  for  the  belief  that  one  or  other 
of  these  artificial  products  of  the  decomposition  of  vegetable 
matters  exists  in  nature,  in  the  form,  and  endowed  with  the 
properties,  of  the  vegetable  constituents  of  mould ;  there  is  not 
the  shadow  of  a  proof  that  one  of  them  exerts  any  influence  on 
the  growth  of  plants,  either  in  the  way  of  nourishment  or  other- 
wise. 

Vegetable  physiologists  have,  without  any  apparent  reason,  im- 
puted the  known  properties  of  the  humus  and  humic  acids  of  che- 
mists to  that  constituent  of  mould  which  has  received  the  same 
name,  and  in  this  way  have  been  led  to  their  theoretical  notions 
respecting  the  functions  of  the  latter  substance  in  vegetation. 

The  opinion  that  the  substance  called  humus  is  extracted  from 
the  soil  by  the  roots  of  plants,  and  that  the  carbon  entering  into 
its  composition  serves  to  nourish  their  tissues,  without  previously 
assuming  another  form,  is  considered  by  many  as  so  firmly  estab- 
lished that  any  evidence  in  its  favor  has  been  deemed  unneces- 
sary :  the  obvious  difference  in  the  growth  of  plants  according  to 
the  known  abundance  or  scarcity  of  humus  in  the  soil,  seemed 
to  afford  incontestable  proof  of  its  correctness.* 

Yet,  this  position,  when  submitted  to  a  strict  examination,  is 
found  to  be  untenable,  and  it  becomes  evident  from  most  con- 
clusive proofs,  that  humus  in  the  form  in  which  it  exists  in 
THE  SOIL,  does  not  yield  the  smallest  nourishment  to  plants. 

The  adherence  to  the  above  incorrect  opinion  has  hitherto  ren- 
dered it  impossible  to  ascertain  the  true  theory  of  the  nutritive 
process  in  vegetables,  and  has  thus  deprived  us  of  our  best  guide 
to  a  rational  practice  in  agriculture.  Any  great  improvement 
in  that  most  important  of  all  arts  is  inconceivable,  without  a 
deeper  and  more  perfect  acquaintance  with  the  substances  which 
nourish  plants,  aod  with  the  sources  whence  they  are  derived  ; 
and  no  other  cause  can  be  discovered  to  account  for  the  fluctuat- 

*  This  remark  applies  more  to  German  than  to  English  botanists  and 
physiologists.  In  England,  the  idea  that  humus,  as  such,  affords  nourish- 
ment to  plants  is  by  no  means  general ;  but  on  the  Continent,  the  viewi 
of  Ber^elius  on  this  subject  have  been  almost  universally  adopted. — ^Ed. 


OF  THE  ASSIMILATION  OF  CARBON. 


ing  and  uncertain  state  of  our  knowledge  on  this  subject  up  to 
the  present  time,  than  that  modern  physiology  has  not  kept  pace 
with  the  rapid  progress  of  chemistry. 

In  the  following  inquiry  we  shall  suppose  the  iruMus  of  vege- 
table physiologists  to  be  really  endowed  with  the  properties 
recognised  by  chemists  in  the  brownish-black  deposits  obtained 
by  precipitating  an  alkaline  decoction  of  mould  or  peat  by  means 
of  acids,  and  which  they  name  humic  acid. 

HuMic  ACID,  when  first  precipitated,  is  a  flocculent  substance, 
is  soluble  in  2500  times  its  weight  of  v/ater,  and  combines  with 
alkalies,  forming  with  lime  and  magnesia  compounds  of  the  same 
degree  of  solubility  (Sprengel). 

Vegetable  physiologists  agree  in  the  supposition  that  by  the 
aid  of  water  humus  is  rendered  capable  of  being  absorbed  by  the 
roots  of  plants.  But  according  to  the  observation  of  chemists, 
humic  acid  is  soluble  only  when  newly  precipitated,  and  becomes 
completely  insoluble  when  dried  in  the  air,  or  when  exposed  in 
the  moist  state  to  the  freezing  temperature  (Sprengel). 

Both  tlie  cold  of  winter  and  the  heat  of  summer,  therefore, 
are  destructive  of  the  solubility  of  humic  acid,  and  at  the  same 
time  of  its  capability  of  being  assimilated  by  plants.  So  that, 
if  it  is  absorbed  by  plants,  it  must  be  in  some  altered  form. 

The  correctness  of  these  observations  is  easily  demonstrated 
by  treating  a  portion  f-f  good  mould  with  cold  water.  The  fluid 
remains  colorless,  and  is  found  to  have  dissolved  less  than 
To~dV"6T  P^^"t  o^'  its  weight  of  organic  matters,  and  to  contain 
merely  the  salts  which  are  present  in  rain-water. 

Decayed  oak-wood,  likewise,  of  which  humic  acid  is  the  prin- 
cipal constituent,  was  found  by  Berzelius  to  yield  to  cold  water 
only  slight  traces  of  soluble  materials  ;  and  I  have  myself  veri- 
fied this  observation  on  the  decayed  wood  of  beech  and  fir. 

These  facts,  which  show  that  humic  acid,  in  its  insoluble  con- 
dition, cannot  serve  for  the  nourishment  of  plants,  have  not 
escaped  the  notice  of  physiologists ;  and  hence  they  have 
assumed  that  the  lime  or  the  different  alkalies  found  in  the  ashes 
of  vegetables,  render  soluble  the  humic  acid,  and  fit  it  for  the 
process  of  assimilation. 

Alkalies  and  alkaline  earths  do  exist  in  the  different  kinds  of 


ABSORPTION  OF  HUMUS. 


{oil,  in  sufficient  quantity  to  form  such  soluble  compounds  with 
lumic  acid. 

Now,  let  us  suppose  that  humic   acid  is  absorbed  by  plants  in 

khe  form  of  that  salt  which  contains  the  largest  proportion  of 

lumic  acid,  namely,  in  the  form  of  humate  of  lime  ;  and  then, 

from  the  known  quantity  of  the  alkaline  bases  contained  in  the 

ishes  of  plants,  let  us  calculate  the  amount  of  humic  acid  which 

might  be  assimilated  in  this  manner.     Let  us  admit,  likewise, 

that  potash,  soda,  and  the  oxides  of  iron  and  manganese  have  the 

5ame  capacity  of  saturation  as  lime  with  respect  to  humic  acid, 

md  then  we  may  take  as  the  basis  of  our  calculation  the  analysis 

if  M.  Berthier,  who  found  that  1000  lbs.  of  dry  fir- wood  yielded 

^•3  lbs.  of  ashes,   and   that  in  every   100  lbs.   of  these    ashes, 

educting  the  chloride   of  potassium,  the  silicate,  and  sulphate 

f  potash,  46-1  lbs.  consisted  of  the  basic  metallic  oxides,  potash, 

coda,  lime,  magnesia,  iron,  and  manganese. 

One  Hessian  acre*  of  woodland  yields  annually,  according  to 
J  >r.  Heyer,  on  an  average,  2650  lbs.  of  dry  fir-wood,  which  con- 
'  lins  10-07  lbs.  of  metallic  oxides. 

Now,  according  to  the  estimates  of  Malaguti  and  Sprengel,  1 
I  J.  of  lime  combines  chemically  with  10*9  lbs.  of  humic  acid  ,' 
1 0*07  lbs.  of  the  metallic  oxides  would  accordingly  introduce 
i.ito  the  trees  nearly  111  lbs.  of  humic  acid,  which,  admitting 
humic  acid  to  contain  58  per  cent,  of  carbon,  would  correspond 
to  165  lbs.  of  dry  wood.  But  we  have  seen  that  2650  lbs.  of 
fir-wood  are  really  produced. 

Again,  if  the  quantity  of  humic  acid  which  might  be  intro- 
duced into  wheat  in  the  form  of  humates,  is  calculated  from  the 
Known  proportion  of  metallic  oxides  existing  in  wheat  straw  (the 
sulphates  and  chlorides  also  contained  in  the  ashes  of  the  straw 
not  being  included),  it  will  be  found  that  the  wheat  growing  on 
one  Hessian  acre  would  receive  in  that  way  57^  lbs.  of  humic 
acid,  corresponding  to  85  lbs.  of  woody  fibre.  But  the  extent 
of  land  just  mentioned  produces,  independently  of  the  roots  and 
grain,  1780  lbs.  of  straw,  the  composition  of  which  is  the  same 
as  that  of  woody  fibre. 

•  One  Hessian  acre  is  equal  to  40,000  square  feet,  Hessian,  or  26,910 
square  feet,  English  measure. 
PART  TI.  2* 


10  or  THE  ASSIMILATION  OF  CARBON. 

It  has  been  taken  for  granted  in  these  calculations,  that  the 
basic  metallic  oxides  which  have  served  to  introduce  humic  acid 
into  the  plants  do  not  return  to  the  soil,  since  it  is  certain  that 
they  remain  fixed  in  the  parts  newly  formed  during  the  process 
of  growth. 

Let  us  now  calculate  the  quantity  of  humic  acid  which  plants 
can  receive  under  the  most  favorable  circumstances,  viz.,  through 
the  agency  of  rain-water. 

ThB  quantity  of  rain  which  falls  at  Erfurt,  one  of  the  most 
fertile  districts  of  Germany,  during  the  months  of  April,  May, 
June,  and  July,  is  stated  by  Schubler  to  be  17^  lbs.  over  every 
Hessian  square  foot  of  surface  (=0*672  square  foot  English)  : 
one  Hessian  acre,  or  26,910  square  feet,  consequently  receive, 
in  round  numbers,  700.000  lbs.  of  rain-water. 

If.  now,  we  suppose  that  the  whole  quantity  of  this  rain  is 
taken  up  by  the  roots  of  a  summer  plant,  which  ripens  fotir 
months  after  it  is  planted,  so  that  not  a  pound  of  water  evaporates 
except  from  the  leaves  of  the  plant ;  and  if  we  further  assume 
that  the  water  thus  absorbed  is  saturated  with  humate  of  lime 
(the  most  generally  diffused  of  the  humates,  and  that  which  con- 
tains the  largest  proportion  of  humic  acid) ;  then  the  plants  thus 
nourished  Would  not  receive  more  than  350  lbs.  of  humic  acid, 
since  one  part  of  humate  of  lime  requires  2000  parts  of  water 
for  solution. 

But  the  extent  of  land  which  we  have  mentioned  produces 
2580  lbs.  of  corn  (in  grain  and  straw,  the  roots  not  included), 
or  20,000  lbs.  of  beet-root  (without  the  leaves  and  small  fibres 
of  the  radicle).  It  is  quite  evident  that  the  350  lbs.  of  humic 
acid,  supposed  to  be  absorbed,  cannot  account  even  for  the 
quantity  of  carbon  contained  in  the  fibres  of  the  radicle  and 
leaves  alone,  even  if  the  supposition  were  correct,  that  the  whole 
of  the  rain-water  was  absorbed  by  the  plants.  But  since  it  is 
known  that  only  a  small  portion  of  ihe  rain-water  which  falls 
upon  the  surface  of  the  earth  is  absorbed  by  plants  and  evapo- 
rates through  their  leaves,  the  quantity  of  carbon  which  can  be 
conveyed  into  them  in  any  conceivable  manner,  by  means  of 
humic  acid,  must  be  almost  inappreciable,  in  comoarison  with 
that  actually  produced  in  vegetation. 


ABSORPTION  OF  HUMUS.  II 

Other  considerations  of  a  higher  nature  confute  the  common 
view  respecting  the  nutritive  office  of  humic  acid,  in  a  manner 
so  clear  and  conclusive  that  it  is  difficult  to  conceive  how  it 
could  have  been  so  generally  adopted. 

Fertile  land  produces  carbon  in  the  form  of  wood,  hay,  grain, 
and  other  kinds  of  growth,  the  masses  of  which  differ  in  a  re- 
markable degree. 

2650  lbs.  of  lirs,  pines,  beeches,  &c.,  grow  annually  as  wood 
upon  one  Hessian  acre  of  forest-land  with  an  average  soil.  The 
same  superficies  yields  2500  lbs.  of  hay. 

A  similar  surface  of  corn-land  gives  from  18,000  to  20,000 
lbs.  of  beet- root ;  or  800  lbs.  of  rye,  and  1780  lbs.  of  straw, — in 
all  2580  lbs. 

One  hundred  parts  of  dry  fir- wood  contain  38  parts  of  carbon  ; 
therefore,  2650  lbs.  contain  1007  lbs.  of  carbon. 

One  hundred  "parts  of  hay,*  dried  in  air,  contain  40*73  parts 
carbon.  Accordingly,  2500  lbs.  of  hay  contain  1018  lbs.  of 
carbon. 

Beet-roots  contain  from  89  to  89-5  parts  water,  and  from  10-5 
to  11  parts  solid  matter,  which  contains  40  per  cent,  of  carbon.f 

20,000  lbs.  of  beet-root  contain,  therefore,  880  lbs.  of  carbon, 
the  quantity  of  this  element  in  the  leaves  and  small  roots  not 
being  included  in  the  calculation. 

One  hundred  parts  of  straw,:}:  dried  in  air,  contain  38  per  cent, 
of  carbon  ;  therefor:^,  1780  lbs.  of  straw  contain  676  lbs.  of 
carbon.  One  hundred  parts  of  corn  contain  43  parts  of  carbon; 
800  lbs.  must  therefore  contain  344  lbs.  ;  in  all  1020  lbs.  of 
carbon. 

*  100  parts  of  hay,  dried  at  100°  C  (212°  F.)  and  burned  with  oxide  of 
copper  in  a  stream  of  oxygen  gas,  yielded  5r93  water,  166  8  caihonicacid, 
and  6S2  of  ashes.  This  gives  45  87  carbon,  5*76  hydrogen.  41*55  oxygen, 
and  6  82  ashes.  Hay,  dried  in  the  air,  loses  ir2  p.  c.  waterat  100<*  C. 
(212°  F.)— Dr.  Will. 

t  I.  0*8075  of  dry  beet  gave  0*416  water  and  1*155  carbonic  acid.  II 
0*400  gave  0*201  water,  and  0*595  carbonic  acid. — Dr.  Will. 

I  Straw  analysed  in  the  same  manner,  and  dried  at  100°  C,  gave  46*3*7 
.p.  c.  of  carbon,  5*68  p.  c.  of  hydrogen,  43*93  p.  c.  of  oxygen  and  4*02  p.  c. 
of  ashes.  Straw  dried  in  the  air  at  100<»  C.  lost  18  p.  c.  -of  water.— Db. 
Will. 


13  OF  THE  ASSIMILATION  OF  CARBON. 


26,910  square  feet  of  wood-land  produce  of  carbon   .  1007  lbs. 

«*                 "             meadow-land            "                .         .  1018  lbs. 

«*                 '«             arable-land,  beet-roots  without  leaves  880  lbs. 

•«                  "             corn                             ....  1020  lbs. 

It  must  be  concluded  from  these  incontestable  facts,  that  equal 
surfaces  of  cultivated  land  of  an  average  fertility  are  capable 
of  producing  equal  quantities  of  carbon  ;  yet,  how  unlike  have 
been  the  different  conditions  of  the  growtli  of  the  plants  from 
which  this  has  been  deduced  ! 

Let  us  now  inquire  whence  the  grass  in  a  meadow,  or  the 
wood  in  a  forest,  receives  its  carbon,  since  there,  carbon  has  not 
been  given  to  it  as  nourishment  ?  and  how  it  happens,  that  the 
soil,  thus  exhausted,  instead  of  becoming  poorer,  becomes  every 
year  richer  in  this  element  ? 

A  certain  quantity  of  carbon  is  taken  every  year  from  the 
forest  or  meadow,  in  the  form  of  wood  or  hay,  and,  in  spite 
of  this,  the  quantity  of  carbon  in  the  soil  augments  ;  it  becomes 
richer  in  humus. 

It  is  said  that  in  fields  and  orchards  all  the  carbon  which  may 
have  been  taken  away  as  leaves,  as  straw,  as  seeds,  or  as  fruit, 
is  replaced  by  means  of  manure  ;  and  yet  this  soil  produces  no 
more  carbon  than  that  of  the  forest  or  meadow,  where  it  is  never 
replaced.  It  cannot  be  conceived  that  the  laws  for  the  nutrition 
of  plants  are  changed  by  culture, — that  the  sources  of  carbon 
for  fruit  or  grain,  and  for  grass  or  trees,  in  meadows  and  forests, 
are  difTerent. 

It  is  not  denied  that  manure  exercises  an  influence  upon  the 
development  of  plants ;  but  it  may  be  affirmed  with  positive  cer- 
tainty, that  to  its  carbon  is  not  due  the  favorable  influence  which 
it  exercises,  because  we  find  that  the  quantity  of  carbon  produced 
by  manured  lands  is  not  greater  than  that  yielded  by  lands  which 
are  not  manured.  The  discussion  as  to  the  manner  in  which 
manure  acts  has  nothing  to  do  with  the  present  question, — which 
is,  the  origin  of  the  carbon.  The  carbon  must  be  derived  from 
other  sources ;  and  as  the  soil  does  not  yield  it,  it  can  only  be 
extracted  from  the  atmosphere. 

In  attempting  to  explain  the  origin  of  carbon  in  plants,  it  has 
never  been  considered  that  the  question  is  intimately  connected 


FERTILITY  OF  DIFFERENT  SOILS.  13 

with  that  of  the  origin  of  humus.     It  is  universally  admitted 
that   humus   arises  from    the   decay   of  plants.     No    primitive 
humus,  therefore,  can  have  existed — for  plants  must  have  pre 
ceded  the  humus. 

Now,  whence  did  the  first  vegetables  derive  their  carbon  ?  and 
in  what  form  is  the  carbon  contained  in  the  atmosphere  ? 

These  two  questions  involve  the  consideration  of  two  most 
remarkable  natural  phenomena,  which,  by  their  reciprocal  and 
uninterrupted  influence,  maintain  the  life  of  individual  animals 
and  vegetables,  and  the  continued  existence  of  both  kingdoms  of 
organic  nature. 

One  of  these  questions  is  connected  with  the  invariable  con- 
dition of  the  air  with  respect  to  oxygen.  One  hundred  volumes 
of  air  have  been  found,  at  every  period  and  in  every  climate,  to 
contain  21  volumes  of  oxygen,  with  such  small  deviations  that 
tliey  must  be  ascribed  to  errors  of  observation. 

Although  the  absolute  quantity  of  oxygen  contained  in  the 
atmosphere  appears  very  great  when  represented  by  numbers, 
yet  it  is  not  inexhaustible.  One  man  consumes  by  respiration 
25  cubic  feet  of  oxygen  in  24  hours ;  10  cwt.  of  charcoal  con- 
sume 32,066  cubic  feet  of  oxygen  during  its  combustion,  so  that 
a  single  iron  furnace  consumes  annually  hundreds  of  millions  of 
cubic  feet ;  and  a  small  town  like  Giessen  (with  about  7000  in- 
habitants) exacts  yearly  from  the  air,  by  the  wood  employed  as 
fuel,  more  than  551  millions  of  cubic  feet  of  this  gas. 

When  we  consider  facts  such  as  these,  our  former  statement, 
that  the  quantity  of  oxygen  in  the  atmosphere  does  not  diminish 
in  the  course  of  ages* — that  the  air  at  the  present  day,  for  exam- 

•  If  the  atmosphere  possessed,  in  its  whole  extent,  the  same  density  as  it 
does  on  the  surface  of  the  sea,  it  would  have  a  height  of  24,555  Parisian 
feet;  but  it  contains  the  vapor  of  water,  so  that  we  may  assume  its  height 
to  be  one  geographical  mile=22,843  Parisian  feet.  Now,  the  radius  of  the 
eai-th  is  equal  to  860  geographical  miles  ;  hence  the 

Volume  of  the  atmosphere=9,307,500  cubic  miles. 
Volume  of  oxygen      .     .     =1,954,578         " 
Volume  of  carbonic  acid     =3,862"7  " 

A  man  daily  consumes  45,000  cubic  inches  (Parisian)  of  oxygen     A  maa 


14  OF  THE  ASSIMILATION  OF  CARBON. 

pie,  does  not  contain  less  oxygen  than  that  found  in  jars  buried  for 
1800  years  in  Pompeii — appears  quite  incomprehensible,  unless 
some  cause  exists  capable  of  replacing  the  oxygen  abstracted. 
How  does  it  happen,  then,  that  the  proportion  of  oxygen  in  the 
atmosphere  is  thus  invariable  ? 

The  answer  to  this  question  depends  upon  another,  namely 
what  becomes  of  the  carbonic  acid  produced  during  the  respira- 
tion of  animals,  and  by  the  process  of  combustion  ?  A  cubic 
foot  of  oxygen  gas,  by  uniting  with  carbon  so  as  to  form  carbonic 
acid,  does  not  change  its  volume.  The  billions  of  cubic  feet  of 
oxygen  extracted  from  the  atmosphere,  are  immediately  supplied 
by  the  same  number  of  billions  of  cubic  feet  of  carbonic  acid. 

The  most  exact  and  trustworthy  experiments  of  De  Saussure, 
made  in  every  season  for  a  space  of  three  years,  have  shown 
that  the  air  contains  on  an  average  0-000415  of  its  own  volume 
of  carbonic  acid  gas  ;  so  that,  allowing  for  the  inaccuracies  of  the 
experiments,  which  must  diminish  the  quantity  obtained,  the  pro- 
portion of  carbonic  acid  in  the  atmosphere  may  be  regarded  as 
nearly  equal  to  nMro"  P^^*^  ^f  its  weight.  The  quantity  varies 
according  to  the  seasons  ;  but  the  yearly  average  remains  cor^ 
tinually  the  same. 

We  have  reason  to  believe  that  this  proportion  was  much 
greater  in  past  ages  ;  and  nevertheless,  the  immense  masses  of 
carbonic  acid  which  annually  flow  into  the  atmosphere  from  sc 
many  causes,  ought  perceptibly  to  increase  its  quantity  from  year 
to  year.     But   we  find  that  all  earlier  observers  describe  its 


yearly  consumes  9505*2  cubic  feet.     1000  million  men  yearly  consume 
9,505,200,000,000  cubic  feet  (Parisian). 

Without  exaggeration  we  may  suppose  that  double  this  quantity  is  con- 
Rumed  in  the  support  of  respiration  of  the  lower  animals,  and  in  the  pro- 
cesses of  decay  and  combustion.  From  this  it  follows,  that  the  annual  con- 
sumption of  oxygen  amounts  to  2*392355  cubic  miles,  or  in  round  numbers 
to  2"4  cubic  miles  Thus,  every  trace  of  oxygen  would  be  removed  from 
the  atmosphere  in  800,000  years.  But  it  would  be  rendered  quite  unfit  for 
the  support  either  of  respiration  or  combustion  in  a  much  shorter  time. 
When  the  quantity  of  oxygen  in  the  air  is  diminished  8  per  cent.,  and  the 
oxygen  thus  abstracted  is  replaced  by  its  own  yolume  of  carbonic  acid,  the 
latter  exerts  a  fatal  action  upon  animal  life,  and  extinguishes  the  combiis- 
tion  of  a  burning  body. 


QUANTITY  OF  OXYGEN  IN  THE  ATMOSPHERE.  1£ 

▼olume  as  from  one-half  to  ten  times  greater  than  that  which  it 
has  at  the  present  time  :  so  that  we  can  hence  at  most  conclude 
that  it  has  diminished. 

It  is  quite  evident  that  the  invariable  quantities  of  carbonic  acid 
and  oxygen  in  the  atmosphere,  must  stand  in  some  fixed  relation 
to  one  another  ;  a  cause  must  exist  which  prevents  the  increase 
of  carbonic  acid  by  removing  that  which  is  constantly  forming  ; 
and  there  must  be  some  means  of  replacing  the  oxygen  removed 
from  the  air  by  the  processes  of  combustion  and  putrefaction,  as 
well  as  by  the  respiration  of  animals. 

Both  these  causes  are  united  in  the  process  of  vegetable  life. 

The  facts  which  we  have  stated  in  the  preceding  pages  prove 
that  the  carbon  of  plants  must  be  derived  exclusively  from  the 
atmosphere.  Now,  carbon  exists  in  the  atmosphere  only  in  the 
form  of  carbonic  acid,  and  therefore  in  a  state  of  combination 
with  oxygen. 

It  has  been  already  mentioned,  that  carbon  and  the  elements  of 
water  form  the  principal  constituents  of  vegetables  ;  the  quantity 
of  the  substances  which  do  not  possess  this  composition  being  in 
a  very  small  proportion.  Now,  the  relative  quantity  of  oxygen 
in  the  whole  mass  is  less  than  in  carbonic  acid ;  for  the  latter 
contains  two  equivalents  of  oxygen,  whilst  one  only  is  required 
to  unite  with  hydrogen  in  the  proportion  to  form  water.  The 
vegetable  products  containing  oxygen  in  larger  proportion  than 
this,  are,  comparatively,  few  in  number ;  indeed,  in  many  the 
hydrogen  is  in  great  excess.  It  is  obvious,  that  when  the  hydro- 
gen of  water  is  assimilated  by  a  plant,  the  oxygen  in  combination 
with  it  must  be  liberated,  and  will  afford  a  quantity  of  this  ele- 
ment sufficient  for  the  wants  of  the  plant.  If  this  be  the  case, 
the  oxygen  contained  in  the  carbonic  acid  is  quite  unnecessary  in 
the  process  of  vegetable  nutrition,  and  it  will  consequently  escape 
into  the  atmosphere  in  a  gaseous  form.  It  is  therefore  certain, 
that  plants  must  possess  the  power  of  decomposing  carbonic  acid, 
since  they  appropriate  its  carbon  for  their  own  use.  The  forma- 
tion of  their  principal  component  substances  must  necessarily  be 
attended  with  the  separation  of  the  carbon  of  the  carbonic  acid 
from  the  oxygen,  which  must  be  returned  to  the  atmosphere, 
whilst  the  carbon  enters  into  combination  with  water  or  its  ele- 


16  OF  THE  ASSIMILATION  OF  CARBON. 

ments.  The  atmosphere  must  thus  receive  a  volume  of  oxygen 
for  every  volume  of  carbonic  acid,  the  carbon  of  which  has  be- 
come a  constituent  of  the  plant. 

This  remarkable  property  of  pla/its  has  been  demonstrated  in 
the  most  certain  manner,  and  it  is  in  the  power  of  every  person 
to  convince  himself  of  its  existence.  The  leaves  and  other  green 
parts  of  a  plant  absorb  carbonic  acid,  and  emit  an  equal  volume 
of  oxygen.  They  possess  this  property  quite  independently  of 
the  plant ;  for,  if  after  being  separated  from  the  stem,  they  are 
placed  in  water  containing  carbonic  acid,  and  exposed  in  that 
condition  to  the  sun's  light,  the  carbonic  acid  is,  after  a  time, 
found  to  have  disappeared  entirely  from  the  water.  If  the  ex- 
periment is  conducted  under  a  glass  receiver  filled  with  water, 
the  oxygen  emitted  from  the  plant  may  be  collected  and  examined. 
When  no  more  oxygen  gas  is  evolved,  it  is  a  sign  that  all  the 
dissolved  carbonic  acid  is  decomposed  ;  but  the  operation  recom- 
mences if  a  new  portion  of  it  is  added. 

Plants  do  not  emit  gas  when  placed  in  water  either  free  from 
carbonic  acid,  or  containing  an  alkali  that  protects  it  from  assi- 
milation. 

These  observations  were  first  made  by  Priestley  and  Senne- 
bier.  The  excellent  experiments  of  De  Saussure  have  further 
shown,  that  plants  increase  in  weight  during  the  decomposition 
of  carbonic  acid  and  separation  of  oxygen.  This  increase  in 
weight  is  greater  than  can  be  accounted  for  by  the  quantity  of 
carbon  assimilated  ;  a  fact  which  confirms  the  view,  that  the  ele- 
ments of  water  are  assimilated  at  the  same  time. 

The  life  of  plants  is  closely  connected  with  that  of  animals,  in 
a  most  simple  manner,  and  for  a  wise  and  sublime  purpose. 

The  presence  of  a  rich  and  luxuriant  vegetation  may  be  con- 
ceived without  the  concurrence  of  animal  life,  but  the  existence 
of  animals  is  undoubtedly  dependent  upon  the  life  and  develop- 
ment of  plants. 

Plants  not  only  afford  the  means  of  nutrition  for  the  growth 
and  continuance  of  animal  organization,  but  they  likewise  furnish 
that  which  is  essential  for  the  support  of  the  important  vital  pro- 
cess of  respiration  ;  for,  besides  separating  all  noxious  matters 
from  the  atmosphere,  they  are  an  inexhaustible  source  of  pure 


ITS  SOURCE  THE  ATMOSPHERE.  17 

oxygen,  and  they  thus  supply  to  the  air  the  loss  constantly  sus- 
tained by  it.  Animals,  on  the  other  hand,  expire  carbon,  while 
plants  inspire  it ;  and  thus  the  composition  of  the  atmosphere, 
the  medium  in  which  both  exist,  is  maintained  constantly  un- 
changed. , 

It  may  be  asked — Is  the  quantity  of  carbonic  acid  in  the  atmo- 
sphere, scarcely  amounting  to  1-lOth  per  cent.,  sufficient  for  the 
wants  of  the  whole  vegetation  on  the  surface  of  the  earth, — is  it 
possible  that  the  carbon  of  plants  has  its  origin  from  the  air  alone  ? 
This  question  is  very  easily  answered.  It  is  known  that  a 
column  of  air  of  1427  lbs.  weight  rests  upon  every  square  Hes- 
sian foot  (=0-567  square  foot  English)  of  the  surface  of  the 
earth  ;  the  diameter  of  the  earth  and  its  superficies  are  likewise 
known,  so  that  the  weight  of  the  atmosphere  can  be  calculated 
with  the  greatest  exactness.  The  thousandth-part  of  this  is  car- 
bonic  acid,  which  contains  upwards  of  27  per  cent,  carbon.  By 
this  calculation  it  can  be  shown,  that  the  atmosphere  contains 
3085  billion  lbs.  of  carbon — a  quantity  which  amounts  to  more 
than  the  weight  of  all  the  plants,  and  of  all  the  strata  of  mineral 
and  brown  coal  existing  on  the  earth.  This  carbon  is,  therefore, 
more  than  adequate  to  supply  all  the  purposes  for  which  it  is  re- 
quired. The  quantity  of  carbon  contained  in  sea-water  is  pro- 
portionally still  greater. 

If,  for  the  sake  of  argument,  we  suppose  the  superficies  of  the 
leaves  and  other  green  parts  of  plants,  by  which  the  absorption 
of  carbonic  acid  is  effected,  to  be  double  that  of  the  soil  upon 
which  they  grow- — a  supposition  much  under  the  truth  in  the 
case  of  woods,  meadows,  and  corn-fields — let  us  further  sup- 
pose, that  from  a  stratum  of  air  two  feet  thick,  resting  on  an  acre 
(Hessian)  of  land,  that  is,  from  80,000  cubic  feet  (Hessian)  of 
air,  there  is  absorbed  in  every  second  of  time,  for  eight  hours 
daily,  carbonic  acid  equal  to  0.00067  of  the  volume  of  the  air, 
or  ToVo'^h  of  its  weight ;  then  those  leaves  would  receive  above 
1000  lbs.  of  carbon  in  200  days.* 

*  The  quantity  of  carbonic  acid  which  can  be  extracted  from  the  air  in 
a  given  time,  is  shown  by  the  following  cnlculation.  During  the  white- 
washing of  a  small  chamber,  the  siuperficies  of  the  walls  and  roof  of  which 
we  will  suppose  to  be  1 05  square  metres,  and  which  receives  six  coats  of 


18  OF  1H£  ASSIMILATION  OF  CARBON. 

But  it  is  inconceivable,  that  the  functions  of  the  organs  of  a 
plant  can  cease  for  any  one  moment  during  its  life,  as  long  as 
those  organs  are  not  exposed  to  the  action  of  a  process  which 
may  counteract  the  performance  of  their  proper  functions.  The 
roots  and  other  parts  of  it,  possessing  the  ^me  property,  con- 
stantly absorb  water  and  carbonic  acid.  This  power  is  inde- 
pendent of  solar  light.  During  the  night,  carbonic  acid  is  accu- 
mulated in  all  parts  of  their  structure  ;  and  the  decomposition  of 
the  carbonic  acid,  the  assimilation  of  the  carbon,  and  the  exha- 
lation of  oxygen,  commence  from  the  instant  that  the  rays  of  the 
sun  strike  them.  As  soon  as  a  young  plant  breaks  through  the 
surface  of  the  ground,  it  begins  to  acquire  color  from  the  top 
downwards ;  arid  the  true  formation  of  woody  tissue  commences 
at  the  same  time. 

The  atmosphere  is  constantly  in  motion,  both  horizontally  and 
vertically.  The  same  spot  is  alternately  supplied  with  air  pro- 
ceeding from  the  poles  or  from  the  equator.  A  gentle  breeze 
moves  in  an  hour  over  six  German  miles,  and  in  less  than  eight 
days  over  the  distance  between  us  and  the  tropics  or  the  poles. 
When  the  vegetable  kingdom  in  the  temperate  and  cold  zones 
ceases  to  decompose  the  carbonic  acid  generated  by  the  processes 
of  respiration  and  combustion,  the  proper,  constant,  and  inex- 
haustible sources  of  oxygen  gas  are  the  tropics  and  warm  cli- 
mates, where  a  sky  seldom  clouded  permits  the  glowing  rays  of 
the  sun  to  shine  upon  an  immeasurably  luxuriant  vegetation.     In 

lime  in  four  days,  carbonic  acid  is  extracted  from  the  air,  and  the  lime  is 
consequently  converted,  on  the  surface,  into  a  carbonate.  It  has  been  ac- 
curately determined  that  one  square  decimetre  receives  in  this  way  a  coat- 
ing of  carbonate  of  lime  weighing  0-732  grammes.  Upon  the  105  square 
metres  already  mentioned  tliere  must  accordingly  be  formed  7680  grammes 
of  carbonate  of  lime,  which  contain  432  )"6  grammes  of  carbonic  acid. 
The  weight  of  one  cubic  decimetre  of  carbonic  acid  being  calculated  at 
two  grammes  (more  accurately  l-QTOVS),  the  above-mentioned  surface  must 
absorb  in  four  days  2'193  cubic  metres  of  carbonic  acid,  2500  square  me- 
tres (one  Hessian  acre)  would  absorb,  under  a  similar  treatment,  51  i  cubic 
metres  =  1S18  cubic  feet  of  carbonic  acid  in  four  days.  In  200  days  it 
would  absorb  2575  cubic  metres  —  904,401  cubic  feet,  which  contain 
11,353  lbs.  of  carbonic  acid,  of  which  3304  lbs.  are  carbon,  a  quantity  three 
times  as  great  as  that  which  is  assimilated  by  the  leaves  and  roots  gro.'^in^; 
upon  the  same  space. 


ITS  SOURCE  THE  ATMOSPHERE.  19 

our  winter,  when  artificial  warmth  must  replace  deficient  heat 
of  the  sun,  carbonic  acid  is  produced  in  superabundance,  and  is 
expended  in  tlie  nourishment  of  tropical  plants.  The  great 
stream  of  air,  which  is  occasioned  by  the  heating  of  the  equator- 
ial regions  and  by  the  revolution  of  the  earth,  carries  with  it  in 
its  passage  to  the  equator  the  carbonic  acid  generated  during  our 
winters  ;  and,  in  its  return  to  the  polar  regions,  brings  with  it  the 
oxygen  produced  by  the  tropical  vegetation. 

The  experiments  of  De  Saussure  have  proved,  that  the  uppei 
strata  of  the  air  contain  more  carbonic  acid  than  the  lower,  which 
are  in  contact  with  plants  ;  and  that  the  quantity  is  greater  by 
night,  than  by  day,  when  it  undergoes  decomposition. 

Plants  thus  improve  the  air,  by  the  removal  of  carbonic  acid, 
and  by  the  renewal  of  oxygen,  which  is  immediately  applied  to 
the  use  of  man  and  animals.  The  horizontal  currents  of  the 
atmosphere  bring  with  them  as  much  as  they  carry  away,  and 
the  interchange  of  air  between  the  upper  and  lower  strata,  caused 
by  their  difference  of  temperature,  is  extremely  trifling  when 
compared  witli  the  horizontal  movements  of  the  winds.  Thus 
vegetable  culture  heightens  the  healthy  state  of  a  country,  so 
that  a  previously  healthy  country  would  be  rendered  quite  unin- 
habitable by  the  cessation  of  all  cultivation. 

The  various  layers  of  wood  and  mineral  coal,  as  well  as  peat, 
form  the  remains  of  a  primeval  vegetation.  The  carbon  con- 
tained in  them  must  have  been  originally  in  the  atmosphere  as 
carbonic  acid,  in  which  form  it  was  assimilated  by  the  plants 
which  constitute  these  formations.  It  follows  from  this,  that  the 
atmosphere  must  be  richer  in  oxygen  at  the  present  time  than  in 
former  periods  of  the  earth's  history.  The  increase  must  be 
exactly  equal  in  volume  to  the  carbonic  acid  abstracted  in  the 
nourishment  of  a  former  vegetation,  and  must,  therefore,  corres- 
pond  to  the  quantity  of  carbon  and  hydrogen  contained  in  the 
carboniferous  deposit.  Thus,  by  the  deposition  of  ten  cubic  feet 
Flessian  (5-51  cubic  feet  English)  of  Newcastle  splint  coal  (of 
the  formula  Cj  4H ,  3O,  and  specific  gravity  1228),  the  atmosphere 
must  have  been  deprived  of  above  eighteen  thousand  cubic  feet 
Hessian  (9918  cubic  feet  English)  of  car/Donic  acid,  and  must 
'nave  been  enriched  with  the  same  tpiantity  of  oxygen.     A  further 


20  OF  THE  ASSIMILATION  OF  CARBON 

quantity  of  oxygen  amounting  to  4480  cubic  feet  Hessian  (2468 
English)  must  have  been  furnished  to  the  air  by  the  decomposi- 
tion of  water,  for  10  cubic  feet  Hessian  of  coal  contains  hydro- 
gen corresponding  to  this  amount.  In  former  ages,  therefore,  the 
atmosphere  must  have  contained  less  oxygen,  but  a  much  larger 
proportion  of  carbonic  acid,  than  it  does  at  the  present  time  ;  q 
circumstance  which  accounts  for  the  richness  and  luxuriance  of 
the  earlier  vegetation.  When  this  became  entombed,  the  condi- 
tions were  established,  under  which  higher  forms  of  animal  life 
were  capable  of  existing.     (Brogniart.) 

But  a  certain  period  must  have  arrived  in  which  the  quantity 
of  carbonic  acid  contained  in  the  air  experienced  neither  increase 
nor  diminution  in  any  appreciable  quantity.  For  if  it  received 
an  additional  quantity  to  its  usual  proportion,  an  increased  vege- 
tation would  be  the  natural  consequence,  and  the  excess  would 
thus  be  speedily  removed.  And,  on  the  other  hand,  if  the  gas  was 
less  than  the  normal  quantity,  the  progress  of  vegetation  would 
be  retarded,  and  the  proportion  would  soon  attain  its  proper  stand- 
ard. When  man  appeared  on  the  earth,  the  air  was  rendered 
constant  in  its  composition. 

The  most  important  function  in  the  life  of  plants,  or,  in  other 
words,  in  their  assimilation  of  carbon,  is  the  separation,  we 
might  almost  say  the  generation,  of  oxygen.  No  matter  can  be 
considered  as  nutritious,  or  as  necessary  to  the  growth  of  plants^ 
which  possesses  a  composition  either  similar  to  or  identical  with 
theirs  ;  because  the  assimilation  of  such  a  substance  could  be 
effected  without  the  exercise  of  this  function.  The  reverse  is 
the  case  in  the  nutrition  of  animals.  Hence  such  substances, 
as  sugar,  starch,  and  gum,  themselves  the  products  of  plaat^, 
cannot  be  adapted  for  assimilation.  And  this  is  rendered  certaui 
by  the  experiments  of  vegetable  physiologists,  who  have  shown 
that  aqueous  solutions  of  these  bodies  are  imbibed  by  the  roots  of 
plants,  and  carried  to  all  parts  of  their  structure,  but  are  not 
assimilated  ;  they  cannot,  therefore,  be  employed  in  their  nutrition. 

In  the  second  part  of  the  work  we  shall  adduce  satisfactory 
proofs  that  decayed  Moody  fibre  (humus)  contains  carbon  and  the 
elements  of  water,  without  an  excess  of  oxygen  ;  its  composition 


SEPARATION  OF  OXYGEN.  91 

(in  100  parts)  differing  from  that  of  woody  fibre  only  in  its  being 
richer  in  carbon. 

Misled  by  this  sinmplicity  in  its  constitution,  physiologists  found 
no  difficulty  in  discovering  the  mode  of  the  formation  of  woody 
fibre ;  for  they  say,*  humus  has  only  to  enter  into  combination 
with  water,  in  order  to  effect  the  formation  of  woody  fibre,  and 
other  substances  similarly  composed,  such  as  sugar,  starch,  and 
gum.  But  they  forget  that  their  own  experiments  have  suffi- 
ciently demonstrated  the  inaptitude  of  these  substances  for  assimi- 
lation. Yet  we  could  scarcely  conceive  a  form  more  fitted  for 
assimilation  than  that  of  the  substances  just  mentioned.  They 
contain  all  the  elements  of  woody  fibre,  and  with  respect  to 
their  composition  in  100  parts,  they  correspond  closely  with 
humus ;  but  they  do  not  nourish  plants. 

All  the  erroneous  opinions  concerning  the  modus  operandi  of 
humus  have  their  origin  in  the  false  notions  entertained  respect- 
ing the  most  important  vital  functions  of  plants ;  analogy,  that 
fertile  source  of  error,  having,  unfortunately,  led  to  the  very 
unapt  comparison  of  the  vital  functions  of  plants  with  those  of 
animals. 

Substances,  such  as  sugar,  starch,  &c.,  containing  carbon  and 
the  elements  of  water,  are  products  of  the  life  of  plants  which 
live  only  whilst  they  generate  them.  The  same  may  be  said  of 
humus,  for  it  can  be  formed  in  plants  like  the  former  substances. 
Smithson,  Jameson,  and  Thomson,  found  that  the  black  excre- 
tions of  unhealthy  elms,  oaks,  and  horse-chestnuts,  consisted  of 
humic  acid  in  combination  with  alkalies.  Berzelius  detected 
similar  products  in  the  bark  of  most  trees.  Now,  can  it  be  sup- 
posed that  the  diseased  organs  of  a  plant  possess  the  power  of 
generating  the  matter  to  which  its  sustenance  and  vigor  are 
ascribed  ? 

How  does  it  happen,  it  may  be  asked,  that  the  absorption  of 
carbon  from  the  atmosphere  by  plants  is  doubted  by  many  bota- 
nists and  vegetable  physiologists,  and  that  by  the  greater  number 
y.Q  purification  of  the  air  by  means  of  them  is  wholly  denied  ? 

'Ihese  doubts  have  arisen  from  an  erroneous  consideration  of 

*  Meyen,  Pflanzenphysiologie,  II.,  S.  141. 


OF  THE  ASSIMILATION  OF  CARBON. 


the  behavior  of  plants  during  the  night.  The  experiments  of 
Ingenhouss  were  in  a  great  degree  the  cause  of  the  uncertainty 
of  opinion  regarding  the  influence  of  plants  in  purifying  the  air. 
His  observation  that  green  plants  emit  carbonic  acid  in  the  dark, 
led  De  Saussure  and  Grischow  to  new  investigations,  by  which 
they  ascertained  that  under  such  conditions  plants  do  really 
absorb  oxygen  and  emit  carbonic  acid  ;  but  that  the  whole  volume 
of  air  undergoes  diminution  at  the  same  time.  From  the  latter 
fact  it  follows,  that  the  quantity  of  oxygen  gas  absorbed  is  greater 
than  the  volume  of  carbonic  acid  separated  ;  for,  if  both  were 
equal,  no  diminution  could  occur.  These  facts  cannot  be  doubt- 
ed, but  the  views  based  on  them  have  been  so  false,  that  nothing, 
except  the  total  disregard  and  the  utmost  ignorance  of  the  chemi- 
cal relations  of  plants  to  the  atmosphere,  can  account  for  their 
adaption. 

It  is  known  that  nitrogen,  hydrogen,  and  a  number  of  other 
gases,  exercise  a  peculiar,  and,  in  general,  an  injurious  influence 
upon  living  plants.  Is  it,  then,  probable,  that  oxygen,  one  of  the 
most  energetic  agents  in  nature,  should  remain  without  influence 
on  plants  when  one  of  their  peculiar  processes  of  assimilation 
has  ceased  ? 

It  is  true  that  the  decomposition  of  carbonic  acid  is  arrested  by 
absence  of  light.  But  then,  namely,  at  night,  a  true  chemical 
process  commences,  in  consequence  of  the  action  of  the  oxygen 
in  the  air,  upon  the  organic  substances  composing  the  leaves, 
blossoms,  and  fruit.  This  process  is  not  at  all  connected  with  the 
life  of  the  vegetable  organism,  because  it  goes  on  in  a  dead  plant 
exactly  as  in  a  living  one. 

The  substances  composing  the  leaves  of  different  plants  being 
known,  it  is  a  matter  of  the  greatest  ease  and  certainty  to  calcu- 
late which  of  them,  during  life,  should  absorb  most  oxygen  by 
chemical  action  when  the  influence  of  light  is  withdrawn. 

The  leaves  and  green  parts  of  all  plants  containing  volatile 
oils  or  volatile  constituents  in  general,  should  absorb  more  than 
other  parts  free  from  such  substances  ;  for  these  change  into  resin 
by  the  absorption  of  oxygen.  Leaves,  also,  containing  either  the 
constituents  of  nut-galls,  or  compounds  in  which  nitrogen  is 
present,  ought  to  absorb  more  oxygen  than  those  destitute  of  such 


INFLUENCE  OF  THE  SHADE  ON  PLANTS.       25 

matters.  The  correctness  of  these  inferences  has  been  distinctly 
proved  by  the  observations  of  De  Saussure  ;  for  whilst  the  taste- 
less and  inodorous  fleshy  leaves  of  the  Agave  Americana  absorb 
only  0.3  of  their  volume  of  oxygen  in  the  dark,  during  twenty- 
four  hours,  the  leaves  of  the  Pinus  Abies,  containing  volatile  and 
resinous  oils,  absorb  ten  times  ;  those  of  the  Quercus  Robur  con- 
taining tannic  acid  14  times ;  and  the  balmy  leaves  of  the  Popu- 
lus  alba  21  times  that  quantity.  This  chemical  action  is  shown 
very  plainly  also  in  the  leaves  of  the  Cotyledon  calycinum,  the 
Cacalia  f,coides,  and  others ;  for  they  are  sour  like  sorrel  in  the 
morning,  tasteless  at  noon,  and  bitter  in  the  evening.  The  forma- 
tion of  acids  is  effected  during  the  night  by  a  true  process  of  oxi- 
dation ;  they  are  deprived  of  their  acid  properties  during  the  day 
and  evening,  and  are  changed  by  separation  of  a  part  of  their 
oxygen  into  compounds  containing  oxygen  and  hydrogen,  either 
in  the  same  proportions  as  in  water,  or  even  with  an  excess  of 
hydrogen  ;  for  such  is  the  composition  of  all  tasteless  and  bitter 
substances. 

Indeed  the  quantity  of  oxygen  absorbed  could  be  estimated 
pretty  nearly  by  the  different  periods  which  the  green  leaves  of 
plants  require  to  undergo  alteration  in  color  by  the  influence  of 
the  atmosphere.  Those  continuing  longest  green  will  abstract 
less  oxygen  from  the  air  in  an  equal  space  of  time,  than  those 
the  constituent  parts  of  which  sufTer  a  more  rapid  change.  It  is 
found,  for  example,  that  the  leaves  of  the  Ilex  aquifolium,  distin- 
guished by  the  durability  of  their  color,  absorb  only  0.86  of  their 
volume  of  oxygen  gas  in  the  same  time  that  the  leaves  of  the 
poplar  absorb  8,  and  those  of  the  beech  9^  times  their  volume : 
both  the  beech  and  poplar  being  remarkable  for  the  rapidity  and 
ease  with  which  the  color  of  their  leaves  changes.  (De 
Saussure.) 

When  the  green  leaves  of  the  beech,  the  oak,  or  the  holly,  are 
dried  under  the  air-pump,  with  exclusion  of  light,  then  moistened 
with  water,  and  placed  under  a  glass  globe  filled  with  oxygen, 
they  are  found  to  absorb  that  gas  in  proportion  as  they  change  in 
color.  The  chemical  nature  of  this  process  is  thus  completely 
established.  The  diminution  of  the  gas  which  occurs  can  only 
be  owing  to  the   union    of  a  large  proportion  of  oxygen  with 


M  OF  THE  ASSIMILATION  OF  CARBON. 


those  substances  already  in  the  state  of  oxides,  or  to  the  oxida- 
tion of  such  vegetable  compounds  as  contain  hydrogen  in  excess. 
The  fallen  brown  or  yellow  leaves  of  the  oak  contain  no  longer 
tannin,  and  those  of  the  poplar  are  destitute  of  balsamic  consti- 
tuents. 

The  property  possessed  by  green  leaves  of  absorbing  oxygen 
belongs  also  to  fresh  wood,  whether  taken  from  a  twig  or  from 
the  interior  of  the  trunk  of  a  tree.  When  fine  chips  of  such  wood 
are  placed  in  a  moist  condition  under  a  jar  filled  with  oxygen, 
the  gas  is  seen  to  diminish  in  volume.  But  wood,  dried  by  ex- 
posure to  the  atmosphere  and  then  moistened,  converts  the 
oxygen  into  carbonic  acid,  without  change  of  volume ;  fresh 
wood,  therefore,  absorbs  most  oxygen.* 

MM.  Petersen  and  Schodler  have  shown,  by  the  careful  ele- 
mentary analysis  of  24  different  kinds  of  wood,  that  they  contain 
carbon  and  the  elements  of  water,  with  the  addition  of  a  certain 
quantity  of  hydrogen.  Oak  wood,  recently  taken  from  the  tree, 
and  dried  at  lOOc*  C.  (212=^  F.),  contains  49*432  carbon,  6-069 
hydrogen,  and  44*499  oxygen. 

The  proportion  of  hydrogen  necessary  to  combine  with  44*499 
oxygen  in  order  to  form  water,  is  J  of  this  quantity,  namely 
5-56  ;  it  is  evident,  therefore,  that  oak  wood  contains  -,\  more 
hydrogen  than  corresponds  to  this  proportion.  In  Pinus  larix, 
P.  abies,  and  P.  picea,  the  excess  of  hydrogen  amounts  to  -f ,  and 
in  Tilia  europea  to  ^,  The  quantity  of  hydrogen  stands  in  some 
relation  to  the  specific  weight  of  the  wood  ;  the  lighter  kinds  of 
wood  contain  more  of  it  than  the  heavier.  In  ebony  wood 
(Diospyros  ehenum)  the  oxygen  and  hydrogen  are  in  exactly  the 
same  proportion  as  in  water. 

The  difference  between  the  composition  of  the  varieties  of 
wood,  and  that  of  simple  woody  fibre,  depends,  unquestionably, 

*  When  villages  situated  on  the  banks  of  rivers  become  inundated  with 
floods,  this  property  of  wood  gives  rise  to  much  disease.  The  wood  of  the 
floors  and  the  rafters  of  the  building  become  saturated  with  water,  which 
evaporates  very  slowly.  The  oxygen  of  the  air  is  absorbed  rapidly  by 
the  moist  wood,  and  carbonic  acid  is  generated.  The  latter  gas  exercise; 
a  directly  pernicious  influence  when  present  in  air  to  the  amount  of  7  at 
8  per  cent. 


EVOLUTION  OF  CARBONIC  ACID  DURING  THE  NJGHT.     25 


upon  the  presence  of  constituents,  in  part  soluble,  and  in  part 
insoluble,  such  as  resin  and  other  matters,  containing  a  large 
proportion  of  hydrogen  :  the  hydrogen  of  such  substances  being 
in  the  analysis  of  the  various  woods  added  to  that  of  the  true 
woody  fibre. 

It  has  previously  been  mentioned  that  mouldering  oak  wood 
contains  carbon  and  the  elements  of  water,  without  any  excess 
of  hydrogen.  If,  in  its  present  state,  its  further  decay  does  not 
alter  the  volume  of  the  air,  it  is  certain  that  in  the  beginning  of 
the  process  the  result  must  have  been  different,  for  the  amount 
of  hydrogen  present  in  the  fresh  wood  has  been  diminished,  and 
this  could  only  have  been  eifected  by  an  absorption  of  oxygen. 

Most  vegetable  physiologists  have  connected  the  emission  of 
carbonic  acid  during  the  night  with  the  absorption  of  oxygen 
from  the  atmosphere,  and  have  considered  these  actions  as  a  true 
process  of  respiration  in  plants,  similar  to  that  of  animals,  and, 
like  it,  having  for  its  result  the  separation  of  carbon  from  some 
of  their  constituents.  This  opinion  has  a  very  weak  and  un- 
stable foundation. 

The  carbonic  acid,  which  has  been  absorbed  by  the  leaves 
and  by  the  roots,  together  with  water,  ceases  to  be  decomposed 
on  the  departure  of  daylight ;  it  is  dissolved  in  the  juices  which 
pervade  all  parts  of  the  plant,  and  escapes  every  moment 
through  the  leaves  in  quantity  corresponding  to  that  of  the  water 
which  evaporates. 

A  soil  in  which  plants  vegetate  vigorously,  contains  a  certain 
quantity  of  moisture  indispensably  necessary  to  their  existence. 
Carbonic  acid,  likewise,  is  always  present  in  such  a  soil, 
whether  it  has  been  abstracted  from  the  air,  or  has  been  gene- 
rated by  the  decay  of  vegetable  matter.  Rain  and  well  water, 
and  also  that  from  other  sources,  invariably  contains  carbonic 
acid.  Plants  during  their  life  constantly  possess  the  power  of 
absorbing  by  their  roots  moisture,  and,  along  with  it,  air  or  car- 
bonic acid.  Is  it,  therefore,  surprising  that  the  carbonic  acid 
should  be  returned  unchanged  to  the  atmosphere  along  with 
water,  in  the  absence  of  light ;  for  this  is  known  to  be  the  cause 
of  the  fixation  of  its  carbon  ? 

Neither  this  emission  of  carbonic  acid  nor  the  absorption  of 
3 


2G  ON  THE  ASSIMIL.iTION  OS  CARBON. 

oxygen  has  any  connexion  with  the  process  of  assimilation,  nor 
have  they  the  slightest  relation  to  one  another ;  the  one  is  a 
purely  mechanical,  the  other  a  purely  chemical  process.  A 
cotton  wick,  inclosed  in  a  lamp  containing  a  liquid  saturated 
with  carbonic  acid,  acts  exactly  in  the  same  manner  as  a  living 
plant  in  the  night.  Water  and  carbonic  acid  are  sucked  up  by 
capillary  attraction,  and  both  evaporate  from  the  exterior  part 
of  the  wick. 

Plants  living  in  a  moist  soil  containing  humus  exhale  much 
more  carbonic  acid  during  the  night  than  those  growing  in  dry 
situations  ;  they  also  yield  more  in  rainy  tlian  in  dry  weather  ; 
these  facts  point  out  to  us  the  cause  of  the  numerous  contra- 
dictory observations  made  with  respect  to  the  change  impressed 
upon  the  air  by  living  plants,  both  in  darkness  and  in  common 
daylight ;  but  these  contradictions  are  unworthy  of  considera- 
tion, as  they  do  not  assist  in  the  solution  of  the  main  question.    - 

There  are  other  facts  which  prove  in  a  decisive  manner  that 
plants  yield  more  oxygen  to  the  atmosphere  than  they  extract 
from  it.  These  proofs  may  easily  be  obtained,  without  having 
recourse  to  any  peculiar  arrangements,  from  observations  made 
on  plants  living  under  water. 

Pools  and  ditches,  the  bottoms  of  which  are  covered  with 
growing  plants,  often  freeze  upon  their  surface  in  winter,  so 
that  the  water  is  completely  excluded  from  the  atmosphere  by 
a  clear  stratum  of  ice  ;  under  such  circumstances  small  bubbles 
of  gas  are  observed  to  escape  continually  during  the  day,  from 
the  points  of  the  leaves  and  twigs.  These  bubbles  are  seen 
most  distinctly  when  the  rays  of  the  sun  fall  upon  the  ice ;  they 
are  very  small  at  first,  but  collect  under  the  ice  and  form  largei 
bubbles.  They  consist  of  pure  oxygen  gas.  Neither  during 
the  night,  nor  during  the  day  when  the  sun  does  not  shine,  are 
they  observed  to  diminish  in  quantity.  The  source  of  this 
oxygen  is  the  carbonic  acid  absorbed  by  the  plants  from  the 
water,  to  which  it  is  again  supplied  by  the  decay  of  vegetable 
substances  contained  in  the  soil.  If  these  plants  absorb  oxygen 
during  the  night,  it  can  be  in  no  greater  quantity  than  that  which 
the  surrounding  water  holds  in  solution  ;  for  the  gas,  which  has 
been  exhaled,  is  not  again  absorbed. 


EVOLUTION  OF  CARBONIC  ACID  DURING  THE  NIGHT.     21 

Sir  H.  Davy  made  an  elegant  experiment  in  illustration  of  the 
facts  just  stated.  He  placed  a  turf,  four  inches  square,  in  a 
porcelain  dish  which  swam  on  the  surface  of  water  impregnated 
with  carbonic  acid  gas.  A  glass  vessel  of  the  capacity  of  230 
cubic  inches  was  made  to  cover  the  grass,  to  which  water  was 
occasionally  supplied  by  a  funnel  furnished  with  a  stopcock. 
The  water  upon  which  the  porcelain  dish  swam  was  daily  sup- 
plied with  new  water  saturated  with  carbonic  acid,  so  that  a 
small  quantity  of  that  gas  must  always  have  been  present  in  the 
receiver.  The  volume  of  air  in  the  receiver  was  found  to  in- 
crease by  exposure  to  daylight,  so  much  so,  that  after  the  lapse 
of  eight  days,  an  increase  of  thirty  cubic  inches  was  observed. 
The  air  inside  the  receiver  on  being  analysed  was  found  to  con- 
tain 4  per  cent,  more  oxygen  than  the  air  of  the  exterior 
atmosphere.  (Davy's  Agricultural  Chemistry,  Lecture  V.)  In 
confirmation  of  the  same  facts  we  may  also  refer  to  the  excellent 
experiments  of  Dr.  Daubeny.* 

In  the  preceding  part  of  the  work,  we  have  furnished  proofs 
that  the  carbon  of  plants  is  derived  from  the  atmosphere.  We 
have  yet  to  consider  the  action  of  humus  and  of  certain  mineral 
matters  upon  the  development  of  vegetation,  and  also  the  source 
whence  plants  receive  their  nitrogen. 

*  On  the  Action  of  Light  upon  Plants,  :  nd  of  Plants  upon  the  Atmos- 
phere, PhiL  Trans.,  Part  I.,  1836 


'A  ON  THE  ORIGIN  AND  ACTION  OF  HUMUS. 


CHAPTER   III. 

On  the  Origin  and  Action  of  Humus. 

It  will  be  shown  in  the  second  part  of  this  work,  that  all  plants 
and  vegetable  structures  undergo  two  processes  of  decomposition 
after  death.  One  of  these  is  named  fermentation^  or  putrefaction  ; 
the  other  decay  or  eremacausis.* 

It  will  likewise  be  shown,  that  decay  is  a  slow  process  of  com- 
bustion,— a  process,  therefore,  in  which  the  combustible  parts  of' 
a  plant  unite  with  the  oxygen  of  the  atmosphere. 

The  decay  of  woody  fibre  (the  principal  constituent  of  all 
plants)  is  accompanied  by  a  phenomenon  of  a  peculiar  kind. 
This  substance,  in  contact  with  air  or  oxygen  gas,  converts  the 
latter  into  an  equal  volume  of  carbonic  acid,  and  its  decay  ceases 
upon  the  disappearance  of  the  oxygen.  If  the  carbonic  acid  be 
removed,  and  oxygen  replaced,  its  decay  recommences,  that  is, 
it  again  converts  oxygen  into  carbonic  acid.  Woody  fibre  con- 
sists of  carbon  and  the  elements  of  water  ;  and  if  we  judge  only 
from  the  products  formed  during  its  decomposition,  and  from 
those  formed  by  pure  charcoal,  burned  at  a  high  temperature, 
we  might  conclude  that  the  causes  were  the  same  in  both  :  the 
decay  of  woody  fibre  proceeds,  therefore,  as  if  no  hydrogen  or 
oxygen  entered  into  its  composition. 

A  very  long  time  is  required  for  the  completion  of  this  process 
of  combustion,  and  the  presence  of  water  is  necessary  for  its 
maintenance  :  alkalies  promote  it,  but  acids  retard  it  ;  all  anti- 
septic substances,  such  as  sulphurous  acid,  the  mercurial  salts, 
empyreumatic  oils,  &c.,  cause  its  complete  cessation. 

•  The  word  eremacausis  was  proposed  by  the  author  some  time  since, 
in  order  to  explain  the  true  nature  of  decay ;  it  is  compounded  from 
hpif^*t  by  degrees,  and  lavais,  burning. 


IT  EVOLVES  CARBONIC  ACID.  39 


Woody   fibre  in  a  state  of    decay    is   the    substance    called 

HUMUS.* 

The  property  of  woody  fibre  to  convert  surrounding  oxygen 
gas  into  carbonic  acid  diminishes  in  proportion  as  its  decay 
advances,  and  at  last  a  certain  quantity  of  a  brown  coaly-looking 
substance  remains,  in  which  this  property  is  entirely  wanting. 
This  substance  is  called  mould  ;  it  is  the  product  of  the  complete 
decay  of  woody  fibre.  Mould  constitutes  the  principal  part  of 
all  the  strata  of  brown  coal  and  peat.  By  contact  with  alkalies, 
such  as  lime  or  ammonia,  a  further  decay  of  mould  is  occa- 
sioned. 

Humus  acts  in  the  same  manner  in  a  soil  permeable  to  air  as 
in  the  air  itself;  it  is  a  continued  source  of  carbonic  acid,  which 
it  emits  very  slowly.  An  atmosphere  of  carbonic  acid,  formed 
at  the  expense  of  the  oxygen  of  the  air,  surrounds  every  particle 
of  decaying  humus.  The  cultivation  of  land,  by  tilling  and 
loosening  the  soil,  causes  a  free  and  unobstructed  access  of  air. 
An  atmosphere  of  carbonic  acid  is  therefore  contained  in  every 
fertile  soil,  and  is  the  first  and  most  important  food  for  the  young 
plants  growing  upon  it. 

In  spring,  when  those  organs  of  plants  are  absent  which  nature 
has  appointed  for  the  assumption  of  nourishment  from  the  atmo- 
sphere, the  component  substances  of  the  seeds  are  exclusively 
employed  in  the  formation  of  the  roots.  Eacii  new  radicle  fibril 
acquired  by  a  plant  may  be  regarded  as  constituting  at  the  same 
time  a  mouth,  a  lung,  and  a  stomach.  The  roots  perform  the 
functions  of  the  leaves  from  the  first  moment  of  their  formation : 
they  extract  from  the  soil  their  proper  nutriment,  namely,  the 
carbonic  acid  generated  by  the  humus. 

By  loosening  the  soil  surrounding  young  plants,  we  favor  the 
access  of  air,  and  the  formation  of  carbonic  acid  ;  and,  on  the 
other  hand,  the  quantity  of  their  food  is  diminished  by  every 
difficulty  which  opposes  the  renewal  of  air.  A  plant  itself  effects 
this  change  of  air  at  a  certain  period  of  its  growth.  The  car- 
bonic acid,   which  protects  the  undecayed  humus  from  further 

*  The  humic  acid  of  chemists  is  a  product  of  the  decomposition  of 
humus  by  alkalies ;  it  does  not  exist  ia  the  humus  of  vegetable  physiolo- 


ON  THE  ORIGIN  AND  ACTION  OF  HUMUS. 


change,  is  absorbed  and  taken  away  by  the  fine  fibres  of  the 
roots,  and  by  the  roots  themselves  ;  this  is  replaced  by  atmo- 
spheric air,  which,  by  its  oxygen,  renews  the  process  of  decay, 
and  forms  a  fresli  portion  of  carbonic  acid.  A  plant  at  this  time 
receives  its  food  both  by  the  roots  and  by  the  organs  above 
ground,  and  advances  rapidly  to  maturity. 

When  a  plant  is  quite  matured,  and  when  the  organs  by  which 
it  obtains  food  from  the  atmosphere  are  formed,  the  carbonic  acid 
of  the  soil  is  no  further  required. 

Deficiency  of  moisture  in  the  soil,  or  its  complete  dryness, 
does  not  now  check  the  growth  of  a  plant,  provided  it  receives 
from  the  dew  and  from  the  atmosphere  as  much  as  is  requisite  for 
the  process  of  assimilation.  During  the  heat  of  summer  it  derives 
its  carbon  exclusively  from  the  atmosphere. 

We  do  not  know  what  height  and  strength  nature  has  allotted 
to  plants  ;  we  are  acquainted  only  with  the  size  which  they 
usually  attain.  Oaks  are  shown,  both  in  London  and  Amsterdam, 
as  remarkable  curiosities,  which  have  been  reared  by  Chinese 
gardeners,  and  are  only  one  foot  and  a  half  in  height,  although 
their  trunks,  barks,  leaves,  branches,  and  whole  habitus,  evince 
a  venerable  age.  The  small  parsnep  grown  at  Teltow,*  when 
placed  in  a  soil  which  yields  as  much  nourishment  as  it  can  take 
up,  increases  to  several  pounds  in  weight. 

The  size  which  a  plant  acquires  in  a  given  time  is  pro- 
portional  to  the  surface  of  the  organs  destined  to  convet 
GOOD  TO  IT.  When  the  surfaces  of  two  plants  are  equal,  their 
increase  depends  upon  the  length  of  time  that  their  absorbing 
powers  remain  in  activity.  The  absorbing  surfaces  of  fir  trees 
are  active  during  the  greater  part  of  the  year,  so  that  (ccBteris 
paribus),  they  increase  more  than  those  trees  which  part  with 
their  foliage  in  autumn.  Each  leaf  furnishes  to  a  plant  another 
mouth  and  stomach. 

The  power  possessed  by  roots  of  taking  up  nourishment  does 
not  cease  as  long  as  nutriment  is  present.  When  the  food  of  a 
plant  is  in  greater  quantity  than  its  organs  require  for  their  own 

•  Teltow  is  a  village  near  Berlin,  where  small  parsneps  are  cultivated 
in  a  Bandy  soil  :  they  are  much  esteemed,  and  weigh  rarely  above  on« 
ounce. 


GROWTH  OK  PLANTS.  31 

'"e:*"?-'  development,  the  superfluous  nutriment  is  not  returned  to 
r>ie  soil,  but  is  employed  in  the  formation  of  new  organs.  The 
conc.nued  supply  of  carbonic  acid  by  means  of  a  soil  rich  in 
numus  must  exert  a  very  marked  influence  on  the  progressive 
t evelopment  of  the  plant,  provided  the  other  conditions  necessary 
to  the  assimilation  of  carbon  are  also  present.  At  the  side  of  a 
cell  already  formed,  another  cell  arises  ;  at  the  side  of  a  twig 
and  leaf,  a  new  twig  and  a  new  leaf  are  developed.  These  new- 
parts  could  not  have  been  formed  had  there  not  been  an  excess 
of  nourishment.  The  sugar  and  mucilage  produced  in  the  seeds, 
form  the  nutriment  of  the  young  plants,  and  disappear  during  the 
development  of  the  buds,  green  sprouts,  and  leaves. 

The  power  of  absorbing  nutriment  from  the  atmosphere,  with 
which  the  leaves  of  plants  are  endowed,  being  proportionate  to 
the  extent  of  their  surface,  every  increase  in  the  size  and  number 
of  these  parts  is  necessarily  attended  with  an  increase  of  nutri- 
tive power,  and  a  consequent  further  development  of  new  leaves 
and  branches.  Leaves,  twigs,  and  branches,  when  completely 
matured,  as  they  do  not  become  larger,  do  not  need  food  for  their 
support.  For  their  existence  as  organs,  they  require  only  tho 
means  necessary  for  the  performance  of  the  special  functions  to 
which  they  are  destined  by  nature ;  they  do  not  exist  on  their 
own  account. 

We  know  that  the  functions  of  the  leaves  and  other  green 
parts  of  plants  are  to  absorb  nutritive  matters  from  the  atmo- 
sphere, and,  with  the  aid  of  light  and  moisture,  to  appropriate 
their  elements.  These  processes  are  continually  in  operation  : 
they  commence  with  the  first  formation  of  the  leaves,  and  do  not 
cease  with  their  perfect  developme*?.l.  But  the  new  products 
arising  from  this  continued  assimilation  are  no  longer  employed 
by  the  perfect  leaves  in  their  own  increase  :  they  serve  for  the 
formation  of  woody  fibre,  and  all  the  solid  matters  of  similar 
composition.  The  leaves  now  produce  sugar,  amylin  or  starch, 
and  acids,  which  were  previously  formed  by  the  roots  when  they 
were  necessary  for  the  development  of  the  stem,  buds,  leaves, 
and  branches  of  the  plant. 

The  organs  of  assimilation,  at  this  period  of  their  life,  receive 
more  nourishment  from  the  atmosphere  than  they  employ  in  their 


32  ON  THE  ORIGIN  AND  ACTION  01'  HUMUS 


own  sustenance ;  and  when  the  formation  of  the  woody  suv 
stance  has  advanced  to  a  certain  extent,  the  expenditure  of  the 
nutriment,  the  supply  of  which  still  remains  the  same,  takes  & 
new  direction,  and  blossoms  are  produced.  The  functions  of  the 
leaves  of  most  plants  cease  upon  the  ripening  of  their  fruil; 
because  the  products  of  their  action  are  no  longer  needed.  They 
now  yield  to  the  chemical  influence  of  the  oxygen  of  the  air, 
generally  sutlor  a  change  in  color,  and  fall  off. 

A  peculiar  transformation  of  the  matter  contained  in  all 
plants  takes  place  in  the  period  between  blossoming  and  the 
ripcniiig  of  the  fruit ;  new  compounds  are  produced,  which 
furnish  constituents:  to  the  blossoms,  fruit,  and  seeds. 

Transforiiiiitions  of  existing  compounds  are  constantly  taking 
place  during  t!ie  whole  life  of  a  plant,  in  consequence  of  which, 
and  as  the  results  of  these  transformations,  there  are  produced 
gaseous  matters  which  are  excreted  by  the  leaves  and  blossoms, 
solid  excrements  deposited  in  the  bark,  and  fluid  soluble  substan- 
ces which  are  eliminated  by  the  roots.  Such  secretions  are  most 
abundant  immediately  belbre  the  formation  and  during  the  con- 
tinuance of  the  blossoms ;  they  diminish  after  the  development 
of  the  fruit.  Substances  containing  a  large  proportion  of  carbon 
are  excreted  by  the  roots  and  absorbed  by  the  soil.  Through 
the  expulsion  of  these  matters  unfitted  for  nutrition,  the  soil 
receives  again  the  greater  part  of  the  carbon  which  it  had  at  first 
yielded  to  the  young  plants  as  food,  in  the  form  of  carbonic  acid. 

The  soluble  matter  thus  acquired  by  the  soil  is  still  capable 
of  decay  and  putrefaction,  and,  by  undergoing  tl  ese  process  s, 
furnishes  renewed  sources  of  nutrition  to  another  generation  of 
plants;  it  becomes  humus.  The  fallen  leaves  of  trees,  and  the 
old  roots  of  grass  in  the  nu  adow,  are  likewise  converted  into 
humus  by  the  same  influence. 

The  carbon  contained  in  the  roots  of  annual  plants,  such  as 
the  corn  plants  and  culinary  vegetables,  is  without  doubt  derived 
principally  from  the  atmosphere.  But  after  the  removal  of  the 
crop,  their  roots  remain  in  the  soil,  and,  undergoing  putrefiction 
and  decay,  furnish  hunms,  or  that  sut -stance  which  is  able  to 
yield  carbonic  acid  to  a  new  vegetation.     A  soil  receives  more 


NOT  INDISPENSABLE  FOR  PLANTS.  33 


carbon  in  this  form,  than  its  decaying  humus  had  formerly  loit 
in  carbonic  acid. 

Plants  do  not  exhaust  the  carbon  of  a  soil  in  the  normal  con- 
dition of  their  growth  ;  on  the  contrary,  they  add  to  its  quantity. 
But  if  it  be  true  that  plants  give  back  more  carbon  to  a  soil  than 
they  take  from  it,  it  is  evident  that  the  amount  of  carbon  which 
is  removed  in  any  shape  in  the  crop  must  have  been  derived  from 
the  atmosphere  in  the  form  of  carbonic  acid.  It  is  well  known 
that  springs  occurring  in  gardens  of  the  richest  vegetable  mould, 
furnish  clear  and  perfectly  colorless  water  destitute  both  of 
humus  and  of  salts  of  humic  acid.  It  is  likewise  known  that 
humates  cannot  be  detected  in  the  springs  of  meadows,  in  the 
waters  of  our  rivers,  or  even  in  acidulous  mineral  waters, 
although  they  contain  a  considerable  quantity  of  alkaline  salts. 
Now  a  simple  consideration  of  these  facts  proves  to  us  either  that 
the  richest  vegetable  mould  is  free  from  humic  acid,  or  that  this 
acid  cannot  be  absorbed  by  plants  through  the  agency  of  water. 
Hence  it  follows  that  the  common  view  of  the  action  of  humus  is 
erroneous.  The  water  resting  upon  a  meadow  is  found  to  be 
iich  in  carbonic  acid  and  alkaline  bases.  Well-water  also  gene- 
rally contains  much  of  the  former  ingredient.  The  influence, 
ihen,  of  humus  or  decaying  vegetable  matter  upon  vegetation,  is 
explained  by  these  facts  in  the  most  clear  and  satisfactory  man- 
ner. Humus,  therefore,  does  not  nourish  plants  by  being  assimi- 
lated in  its  soluble  state,  but  by  furnishing  a  gradual  and  conti- 
nued source  of  carbonic  acid.  This  gas  forms  the  chief  means  of 
nourishment  to  the  roots  of  plants,  and  is  constantly  formed  anew 
as  long  as  the  soil  admits  the  free  access  of  air  and  moisture, 
these  being  the  necessary  conditions  for  effecting  the  decay  ot 
vegetable  matter. 

The  verdant  plants  of  warm  climates  are  very  often  such  as 
obtain  from  the  soil  only  a  point  of  attachment,  and  are  not  de* 
pendent  on  it  for  their  growth.  How  extremely  small  are  the 
roots  of  the  various  species  of  Cactus,*  Sedum,  and  Sempervivum, 

*  The  Cactus"  was  probably  introduced  into  Sicily  by  the  Spaniards.     It 

forms  as  important  an  article  of  diet  with  the  inhabitants  of  that  island  as 

the  potatoe  does  with  ourselves.      This  abundant,  cooling,  and  juicy  fruit 

fcrms  the  principal  food  of  the  lower  classes  for  three  months,  and  is  con- 

3* 


94  ON  THE  ORIGIN  AND  ACTION  OF  HTTMUS. 

in  proportion  to  their  mass,  and  to  the  surface  of  their  leaves ! 
Large  forests  are  often  found  growing  in  soils  absolutely  desti- 
tute  of  carbonaceous  matter  :  and  the  extensive  prairies  of  the 
Western  Continent  show  that  the  carbon  necessary  for  the  suste- 
nance of  a  plant  may  be  entirely  extracted  from  the  atmosphere. 
Again,  in  the  most  arid  and  barren  sand,  where  it  is  impossible 
for  nourishment  to  be  obtained  through  the  roots,  we  see  the 
milky-juiced  plants  attain  complete  perfection.  The  moisture 
necessary  for  the  nutrition  of  these  plants  is  derived  from  the 
atmosphere,  and  when  assimilated  is  secured  from  evaporation 
by  the  nature  of  the  juice  itself.  Caoutchouc  and  wax,  which 
are  formed  in  these  plants,  surround  the  water,  as  in  oily  emul- 
sions, with  an  impenetrable  envelope  by  which  the  fluid  is 
retained,  in  the  same  manner  as  milk  is  prevented  from  evapo- 
rating by  the  skin  which  forms  upon  it.  The  plants  become 
turgid  with  their  juices. 

sidered  very  palatable,  although  strangers  usually  find  it  insipid.  The 
hills  of  Palermo  covered  with  the  Cactus  correspond  to  our  corn-fields. 
It  is  a  very  important  plant  for  such  districts,  because  its  roots  easily  enter 
into  the  cracks  and  crevices  of  the  volcanic  rocks.  These,  although 
destitute  of  humus,  soon  acquire  it  by  the  decay  of  the  leaves,  and  thus 
fertile  soils  are  gradually  formed  for  other  plants.  {A^utlandcy  S.  274, 
3d  October,  1842.) 


ASSIMILATION  OF  HYDROGEN, 


CHAPTER   IV. 

Oil  the  Assimilation  of  Hydrogen. 

The  atmosphere  contains  the  principal  food  of  plants  in  the 
form  of  carbonic  acid,  in  the  state,  therefore,  of  an  oxide.  The 
solid  part  of  plants  (woody  fibre)  contains  carbon  and  the  consti- 
tuents of  water,  or  the  elements  of  carbonic  acid,  together  with  a 
certain  quantity  of  hydrogen.  It  has  formerly  been  n)entioned 
that  water  consists  of  the  two  gases,  oxygen  and  hydrogen.  We 
can  conceive  tlic  wood  to  arise  from  a  combination  of  the 
carbon  of  the  carbonic  acid  with  the  elements  of  water,  under 
the  influence  of  solar  light.  In  this  case,  72-.35  parts  of  oxygen, 
by  weight,  must  be  separated  as  a  gas  for  every  27-65  parts  of 
carbon  assimilated  by  a  plant ;  for  this  is  the  composition  of  car- 
bonic acid  in  100  parts.  Or,  what  is  much  more  probable, 
plants,  under  the  same  circumstances,  may  decompose  water,  in 
which  case  the  hydrogen  would  be  assimilated  along  with  car- 
bonic acid,  whilst  its  oxygen  would  be  separated.  If  the  latter 
change  takes  place,  9*77  parts  of  hydrogen  must  unite  with  100 
parts  of  carbonic  acid  in  order  to  form  woody  fibre,  and  the 
72 -35  parts  by  weight  of  oxygen,  which  was  in  combination  with 
the  hydrogen  of  the  vater,  and  which  exactly  corresponds  in 
;juantity  with  the  oxygen  contained  in  the  carbonic  acid,  must 
be  separated  in  a  gaseous  form.* 

Each    acre    of  land,    producing    10    cwts.    of   carbon,  gives 

*  As  far  as  regards  the  final  results,  it  is  a  matter  of  perfect  indiffer- 
ence to  which  of  these  views  we  accord  the  preference.  Hence  we  will 
use  both  occasionally.  The  decomposition  of  carbonic  acid,  as  well  as 
that  of  water,  must  be  supposed  in  the  formation  of  those  compounds 
in  which  oxygen  is  either  entirely  absent  or  insufficient  to  form  water 
with  the  hydrogen. 


36  ASSIMILATION  C^i-'  HYDROGEN. 

annually  to  the  atmosphere  2865  lbs.,  or  32,007  cubic  feet  of 
free  oxygen  gas.* 

An  acre  of  meadow,  wood,  or  cultivated  land,  in  general  re- 
places, therefore,  in  the  atmosphere  as  much  oxygen  as  is 
exhausted  by  10  cwts.  of  carbon,  either  in  its  ordinary  combus- 
tion in  the  air,  or  in  the  respiratory  process  of  animals. 

It  has  been  mentioned  in  a  former  part  of  the  work  that  pure 
woody  fibre  contains  carbon  iind  the  component  parts  of  water, 
but  that  ordinary  wood  contains  more  hydrogen  than  corresponds 
to  this  proportion.  This  excess  is  owing  to  the  presence  of  the 
green  principle  of  the  leaf,  wax,  oil,  resin,  and  other  bodies  rich 
in  hydrogen.  Water  must  be  decomposed,  in  order  to  furnish 
the  excess  of  this  element,  and  consequently  one  equivalent  of 
oxygen  must  be  given  back  to  the  atmosphere  for  every  equiva- 
lent of  hydrogen  appropriated  by  a  plant  to  the  production  of 
those  substances.  The  quantity  of  oxygen  thus  set  at  liberty 
cannot  be  insignificant,  for  the  atmosphere  must  receive  above 
100  cubic  feet  of  oxygen  for  every  pound  of  hydrogen 
assimilated. 

It  has  already  been  stated,  that  a  plant,  in  the  formation  of 
woody  fibre,  must  always  yield  to  the  atmosphere  the  same  pro- 
portional quantity  of  oxygen  ;  and  that  the  volume  of  this  gas 
set  free  would  be  the  same  whether  it  were  due  to  the  decompo- 
sition of  carbonic  acid  or  of  water.  It  was  considered  most  pro- 
bable that  the  latter  was  the  case. 

From  their  generating  caoutchouc,  wax,  fats,  and  volatile  oils 
containing  hydrogen  in  large  quantity,  and  little  oxygen,  we  may 
be  certain  that  plants  possess  the  property  of  decomposing 
water,  because  from  no  other  body  could  the  unazotized  sub- 
stances obtain  their  hydrogen.  It  has  also  been  proved  by  the 
observations  of  Humboldt  on  the  fungi,  that  water  may  be  decom- 
posed without  the  assimilation  of  hydrogen.  Water  is  b  remark- 
able combination  of  two  elements,  which  have  the  power  to  sepa- 
rate themselves  from  one  another^  in  innumerable  processes,  in 
a  manner  imperceptible    to   our  senses ;   while  carbonic    acid, 

•  The  specific  weight  of  oxygen  is  expressed  by  the  number  ri026  ; 
hence,  1  cubic  metre  of  oxygen  weighs  3-157  lbs.,  and  2865  lbs.  of  oxygen 
conespond  to  90S  cubic  metres,  or  32,007  cubic  feet 


\SSIMILATION  OF  HYDROGEN. 


on   the   contrary,    is   only   decomposable    by   violent  chemical 
action. 

Most  vegetable  structures  contain  hydrogen  in  the  form  of 
water,  which  can  be  separated  as  such,  and  replaced  by  other 
bodies ;  but  the  hydrogen  essential  to  their  constitution  cannot 
possibly  exist  in  the  state  of  water. 

All  the  hydrogen  necessary  for  the  formation  of  an  organic 
compound  is  supplied  to  a  plant  by  the  decomposition  of  water. 
The  process  of  assimilation,  in  its  most  simple  form,  consists  in  the 
extraction  of  hydrogen  from  water,  and  of  carbon  from  carbonic 
acid,  in  consequence  of  which,  either  all  the  oxygen  of  the 
water  and  of  the  carbonic  acid  is  separated,  as  in  the  formation 
of  caoutchouc,  the  volatile  oils  containing  no  oxygen,  and  other 
similar  substances,  or  only  a  part  of  it  is  exhaled. 

The  known  composition  of  the  organic  compounds  most  gene- 
rally present  in  vegetables,  enables  us  to  state  in  definite  propor 
tions  the  quantity  of  oxygen  separated  during  their  formation. 

36  eq.  carbonic  acid  and  22  eq.  hydrogen  derived  )  __  tj/-^^^..  wihre  * 

from  22  eq.  water S 

with  the  separation  of  72  eq.  oxycren. 
3G  eq.  carbonic  acid  and  36  e'j.  hydrogen  derived   )  ^==.Suear 
from  36  eq.  water     -----      3  &     • 

with  the  separation  of  72  eq.  oxygen. 
36  eq.  carbonic  acid  and  30  eq.  hydrc^ea  derived  >  =: starch 

from  30  eq.  water > 

with  the  separation  of  ^2  eq.  oxygen. 
36  eq.  carbonic  acid  and  lJi3  eq.  hrlroge.i  derived  )  =:2^annic  Acid 

from  16  eq.  water ) 

with  the  separati  jii  of  64  eq   oxygen. 
36  eq.  carbonic  acid  and  18  eq.  hydrogen  derived  )  _  tt^^^^^-^  jj^id 

from  18  eq.  water ) 

with  the  separation  of  4-5  eq.  oxygen. 
36  eq.  carbonic  acid  and  IS  eq.  hydrogen  derived  >  _  j^ff^n^  ^q^td 

from  18  eq.  water ) 

with  the  separation  of  54  eq.  oxygen. 

*  It  is  evident  that  both  carbonic  acid  and  water  must  be  decomposed 
to  yield  woody  fibre  of  the  above  composition,  C3  g  H2  2  O2  2  ;  that  is,  if 
water  is  here  decomposed.  For  22  eq.  of  water  can  only  yield  22  eq.  of 
oxygen  ;  and,  therefore,  supposing  all  the  water  to  be  decomposed,  25  of 
the  36  eq  of  carbonic  acid  must  also  be  decomposed,  to  yield,  with  the 
oxygen  of  the  22  eqs.  of  water,  72  eq,  of  oxygen.  The  remaining  11  eqs. 
of  carbonic  acid  with  the  carbon  of  the  25  eq.  decomposed,  and  the  22  eqs 
of  hydrogen  will  then  yield  the  residue  C  3  6  Ha  2  O2  2. 


ASSIMILATION  OF  HYDROGEN. 


30  eq.  carbonic  acid  and  24  eq.  hydrogen  derived  )  =Oil  ofTuroenttne 

from  24  eq.  water 5  J        P 

with  the  separation  of  84.  eq.  oxygen. 

It  will  readily  be  perceived  that  the  formation  of  the  acids  is 
accompanied  with  the  smallest  separation  of  oxygen;  that  the 
amount  of  oxygen  set  free  increases  with  the  production  of  the 
so-named  neutral  substances,  and  reaches  its  maximum  in  the 
formation  of  the  oils.  Fruits  remain  acid  in  cold  summers ; 
while  the  most  numerous  trees  under  the  tropics  are  those  which 
produce  oils,  caoutchouc,  and  other  substances  containing  very 
little  oxygen.  The  action  of  sunshine  and  influence  of  heat 
upon  the  ripening  of  fruit  is  thus,  in  a  certain  measure,  repre- 
sented by  the  numbers  above  cited. 

The  green  resinous  principle  of  the  leaf  diminishes  in  quan- 
tity, while  oxygen  is  absorbed,  when  fruits  are  ripened  in  the, 
dark ;  red  and  yellow  coloring  matters  are  formed ;  tartaric, 
citric,  and  tannic  acids  disappear,  and  are  replaced  by  sugar, 
amylin,  or  gum.  6  eq.  Tartaric  acid,  by  absorbing  6  eq.  oxygen 
from  the  air,  form  grape  sugar,  with  the  separation  of  12  eq. 
carbonic  acid,  1  eq.  Tannic  Acid,  by  absorbing  8  eq.  oxygen 
from  the  air,  and  4  eq.  water,  form  1  eq.  of  Amylin,  or  starch, 
with  separation  of  6  eq.  carbonic  acid. 

We  can  explain,  in  a  similar  manner,  the  formation  of  all  the 
unazotized  component  substances  of  plants,  whether  they  are 
produced  from  carbonic  acid  and  water,  with  the  separation  of 
oxygen,  or  by  the  conversion  of  one  substance  into  the  other, 
by  the  assimilation  of  oxygen  and  separation  of  carbonic  acid. 
We  do  r^ot  know  in  what  form  the  production  ofthe.se  constitu- 
ents takes  place  ;  in  this  respect,  the  representation  of  their 
fDrmation  which  we  have  given  must  not  be  received  in  an 
absolute  sense,  it  being  intended  only  to  render  the  nature  of 
the  process  more  capable  of  apprehension  ;  but  i'  must  not  be 
forgotten,  that  if  the  conversion  of  tartaric  acid  into  sugar,  in 
grapes,  be  considered  as  a  fact,  it  must  take  place  under  hU  cir- 
cumstances in  the  proportions  aMve  mentioned. 

The  vital  process  in  plants  is,  vjth  reference  to  the  point  we 
have  been  considering,  the  converse  of  the  chemical  processes 
engaged  in  the  formation  of  salts.      Carbonic  acid,  zinc,  and 


ATTENDED  WITH  EVOLUTION  OF  OXYGEN.      39 

water,  when  brought  into  contact,  act  upon  one  another,  and 
HYDROGEN  IS  SEPARATED,  while  a  White  pulverulent  compound  is 
formed,  which  contains  carbonic  acid,  zinc,  and  the  oxygen  of 
the  water.  A  living  plant  represents  the  zinc  in  this  process  : 
but  the  process  of  assimilation  gives  rise  to  compounds,  which 
contain  the  elements  of  carbonic  acid  and  the  hydrogen  of 
water,  whilst  oxygen  is  separated. 

Decay  has  been  described  above  as  the  great  operation  of  na- 
ture, by  which  that  oxygen  which  was  assimilated  by  plants 
during  life,  is  again  returned  to  the  atmosphere.  During  the 
progress  of  growth,  plants  appropriate  carbon  in  the  form  of 
carbonic  acid,  and  hydrogen  from  the  decomposition  of  water, 
•he  oxygen  of  which  is  set  free,  together  with  a  part  or  all  of 
ihat  contained  in  the  carbonic  acid.  In  the  process  of  putrefac- 
tion, a  quantity  of  woter,  exactly  corresponding  to  that  of  the 
hydrogen,  is  again  formed  by  extraction  of  oxygen  from  the  air ; 
while  all  the  oxygen  of  the  organic  matter  is  returned  to  the 
atmosphere*  in  the  fJ^rm  of  carbonic  acid.  Vegetahle  matters 
can  emit  carbonic  acid,  during  their  decay,  only  in  proportion 
to  the  quantity  of  oxygen  which  they  contain  ;  acids,  therefore, 
yield  more  carbonic  acid  than  neutral  compounds  ;  while  fatty 
acids,  resin,  and  wax,  do  not  putrefy  ;  t  ley  remain  in  the  soil 
without  any  apparent  change. 


40  SOURCE  AND  ASSIMILATION  OF  NITROGEN. 


CHAPTER  V. 


We  cannot  suppose  that  a  plant  could  attain  maturity,  even  in 
the  richest  vegetable  mould,  without  the  presence  of  mattei 
containing  nitrogen  ;  since  we  know  that  nitrogen  exists  in 
every  part  of  the  vegetable  structure.  The  first  and  most  im- 
portant question  to  be  solved,  therefore,  is  :  How  and  in  what 
form  does  nature  furnish  nitrogen  to  vegetable  albumen,  and' to 
gluten,  or  to  fruits  and  seeds  ?  * 

This  question  is  susceptible  of  a  very  simple  solution. 

Plants,  as  we  know,  grow  perfectly  well  in  a  mixture  of  char- 
coal and  earth,  previously  calcined,  if  supplied  at  the  same  time 
with  rain-water.  Rain-water  can  contain  nitrogen  only  in  three 
forms,  as  dissolved  atmospheric  air,  as  nitric  acid,  or  as  ammonia. 
Now,  the  nitrogen  of  the  air  cannot  be  made  to  enter  into  combi- 
nation with  any  element  except  oxygen,  even  by  the  employment 
of  the  most  powerful  chemical  means.  We  have  not  the  slight- 
est reason  for  believing  that  the  nitrogen  of  the  atmosphere  takes 
part  in  the  processes  of  assimilation  of  plants  and  animals  ;  on  the 
contrary,  we  know  that  many  plants  emit  the  nitrogen  which  is 
absorbed  by  their  roots,  either  in  the  gaseous  form,  or  in  solution 
in  water.  But  there  are  on  the  other  hand  numerous  facts, 
showing,  that  the  formation  in  plants  of  substances  containing 
nitrogen,  such  as  gluten,  takes  place  in  proportion  to  the  quantity 

*  "  It  is  certain,"  says  Saussure,  "  from  the  experiments  which  have 
been  made  on  this  point,  that  plants  receive  their  nitrogen  only  from  such 
animal  or  vegetable  extracts,  or  from  such  ammoniacal  vapors  as  they  may 
find  in  the  soil,  or  extract  from  the  air.  When  plants  are  made  to 
vegetate  by  the  aid  of  water  in  a  confined  atmosphere,  we  may  presume 
that  the  new  parts  can  only  obtain  nitrogen  at  the  expense  of  other  parta 
to  which  it  had  formerly  been  supplied."     {^De  Saussure,  page  190.) 


SOURCE  AND  ASSIMILATION  OF  NITROGEN.  41 


of  this  element  conveyed  to  their  roots  in  the  state  of  ammonia, 
derived  from  the  putrefaction  of  animal  matter. 

Ammonia,  too,  is  capable  of  undergoing  such  a  multitude  of 
transformations,  when  in  contact  with  other  bodies,  that  in  this 
respect  it  is  not  inferior  to  water,  which  possesses  the  same  pro- 
perty in  an  eminent  degree.  It  possesses  properties  which  we 
do  not  find  in  any  other  compound  of  nitrogen ;  when  pure,  it  is 
extremely  soluble  in  water  ;  it  forms  soluble  compounds  with  all 
the  acids  ;  and  when  in  contact  with  certain  other  substances,  it 
completely  resigns  its  character  as  an  alkali,  and  is  capable  of 
assuming  the  most  various  and  opposite  forms.  Formate  of  am- 
monia changes,  under  the  influence  of  a  high  temperature,  into 
hydrocyanic  acid  and  water,  without  the  separation  of  any  of  its 
elements.  Ammonia  forms  urea,  with  cyanic  acid,  and  a  series 
of  crystalline  compounds,  with  the  volatile  oils  of  mustard  and 
bitter  almonds.  It  changes  into  splendid  blue  or  red  coloring 
matters,  when  in  contact  with  phloridzia,  the  bitter  constituent  of 
the  bark  of  the  root  of  the  apple-tree,  with  orcin,  the  sweet  prin- 
ciple of  the  Lichen  dealhatus,  or  with  erythrin,  the  tasteless  matter 
of  the  Rocella  tinctoria.  All  blue  coloring  matters  capable  of 
being  reddened  by  acids,  and  all  red  coloring  substances  rendered 
blue  by  alkalies,  contain  nitrogen,  but  not  in  the  form  of  a  base. 

These  facts  are  not  sufficient  to  establish  the  opinion  that  it  is 
ammonia  which  affords  all  vegetables,  without  exception,  the  ni- 
trogen of  their  constituent  substances.  Considerations  of  another 
kind,  however,  give  to  this  opinion  a  degree  of  certainty  which 
completely  excludes  all  other  views  of  the  matter. 

Let  us  picture  to  ourselves  the  condition  of  a  well-cultured 
farm  so  large  as  to  be  independent  of  assistance  from  other 
quarters.  On  this  extent  of  land  there  is  a  certain  quantity  of 
nitrogen  contained  both  in  the  corn  and  fruit  which  it  produces, 
and  in  the  men  and  animals  which  feed  upon  them,  and  also  in  their 
excrements.  We  shall  suppose  this  quantity  to  be  known.  The 
land  is  cultivated  without  the  importation  of  any  foreign  sub- 
stance containing  nitrogen.  Now,  the  products  of  this  farm 
must  be  exchanged  every  year  for  money,  and  other  necessaries 
of  life — for  bodies,  therefore,  destitute  of  nitrogen.  A  certain 
proportion  of  nitrogen  is  exported  in  tiie  shape  of  corn  and  cat- 


42  SOURCE  AND  ASSIMILATION  OF  NITROGEN. 

tie :  and  this  exportation  takes  place  every  year,  without  the 
smallest  compensation  :  yet  after  a  given  number  of  years,  the 
quantity  of  nitrogen  will  be  found  to  have  increased.  Whence, 
we  may  ask,  comes  this  increase  of  nitrogen  ?  The  nitrogen  in 
the  excrements  cannot  reproduce  itself,  and  the  earth  cannot  yield 
it.  Plants,  and  consequently  animals,  must,  therefore,  derive 
their  nitrogen  from  the  atmosphere.     (Boussingault.) 

It  will  in  a  subsequent  part  of  this  work  be  shown  that  the 
last  products  of  the  decay  and  putrefaction  of  animal  bodies  pre- 
sent themselves  in  two  different  forms.  They  are  in  the  form  of 
ammonia  (a  combination  of  hydrogen  and  nitrogen),  in  the  tem- 
perate and  cold  climates,  and  in  that  of  nitric  acid  (a  compound 
containing  oxygen),  in  the  tropics  and  hot  climates.  The  forma- 
tion of  the  latter  is  always  preceded  by  the  production  of  the 
former.  Ammonia  is  the  last  product  of  the  putrefaction  ,of 
animal  bodies ;  nitric  acid  is  the  product  of  the  decay  or  erema- 
causis  of  ammonia.  A  generation  of  a  thousand  million  men  is 
renewed  every  thirty  years  ;  thousands  of  millions  of  animals 
cease  to  live,  and  are  reproduced,  in  a  much  shorter  period. 
Where  is  the  nitrogen  contained  in  them  during  life  ?  There  la 
no  question  which  can  be  answered  with  more  positive  certainty. 
All  animal  bodies  during  their  decay  yield  to  the  atmosphere 
their  nitrogen  in  the  form  of  animonia.  Even  in  the  bodies 
buried  sixty  feet  under  ground  in  the  churchyard  of  the  Eglise 
des  Innocens,  at  Paris,  all  the  nitrogen  contained  in  the  adipocire 
was  in  the  state  of  ammonia.  Ammonia  is  the  simplest  of  all 
the  compounds  of  nitrogen ;  and  hydrogen  is  the  element  for 
which  nitrogen  possesses  the  most  predominant  affinity. 

The  nitrogen  of  putrefied  animals  is  contained  in  the  atmo- 
sphere as  ammonia,  in  the  state  of  a  gas  which  is  capable  of 
entering  into  combination  with  carbonic  acid,  and  of  forming  a 
volatile  salt.  Ammonia  in  its  gaseous  form,  as  well  as  all  its 
volatile  compounds,  is  of  extreme  solubility  in  water.  Ammonia, 
therefore,  cannot  remain  long  in  the  atmosphere,  as  every  shower 
of  rain  must  effect  its  condensation,  and  convey  it  to  the  surface 
of  the  earth.  Hence  also,  rain-water  must  at  all  times  contain 
ammonia,  though  not  always  in  equal  quantity.  It  must  contain 
more  in  summer  than  in  spring  or  in  winter,  because  the  inter 


PRODUCTS  OF  PUTREFACTION.  43 

vals  of  time  between  the  showers  are  in  summer  greater ;  and 
when  several  wet  days  occur,  the  rain  of  the  first  must  contain 
more  of  it  than  that  of  the  second.  The  rain  of  a  thunder-storm, 
after  a  long- protracted  drought,  ought  for  this  reason  to  contain 
the  greatest  quantity  conveyed  to  the  earth  at  one  time. 

But  all  the  analyses  of  atmospheric  air  hitherto  made  have 
failed  to  demonstrate  the  presence  of  ammonia,  although,  accord- 
ing to  our  view,  it  can  never  be  absent.  Is  it  possible  that  it 
could  have  escaped  our  most  delicate  and  most  exact  apparatus  ? 
The  quantity  of  nitrogen  contained  in  a  cubic  foot  of  air,  as  am- 
monia, is  certainly  extremely  small,  but,  notwithstanding  this, 
the  sum  of  the  quantities  of  nitrogen  from  thousands  and  millions 
of  dead  animals  is  more  than  sufficient  to  supply  all  those  living 
at  one  time  with  this  element. 

From  the  tension  of  aqueous  vapor  at  15°  C.  (59^  F.)=0,98 
lines  (Paris  measure),  and  from  its  known  specific  gravity  at 
0°  C.  (32®  F.),  it  follows  that  when  the  temperature  of  the  air  is 
59°  F.  and  the  height  of  the  barometer  28^^,  1  cubic  metre,  or 
35-3  cubic  feet  of  aqueous  vapor  are  contained  in  48-1  cubic 
metres,  or  1698  cubic  feet  of  air  ;  35-3  cubic  feet  of  aqueous 
vapor  weigh  about  I5  lb.  Consequently,  if  we  suppose  that 
the  air  saturated  with  moisture  at  59°  F.  allows  all  the  water 
which  it  contains  in  the  gaseous  form  to  fall  as  rain,  then  1  pound 
of  rain. water  must  be  obtained  from  every  1132  cubic  feet  of 
air.  The  whole  quantity  of  ammonia  contained  in  the  same 
number  of  cubic  feet  will  also  be  returned  to  the  earth  in  this 
one  pound  of  rain-water.  But  if  the  1132  cubic  feet  of  air  con- 
tain a  single  grain  of  ammonia,  then  the  few  cubic  inches  usually 
employed  in  an  analysis  must  contain  only  0-0000048  of  a 
grain.  This  extremely  small  proportion  is  absolutely  inappre- 
ciable by  the  most  delicate  and  best  eudiometer ;  it  might  be 
classed  among  the  errors  of  observation,  even  were  its  quantity 
ten  thousand  times  greater.  But  the  detection  of  ammonia  must 
be  much  more  easy  when  a  pound  of  rain-water  is  examined, 
for  this  contains  all  the  gas  that  was  diffused  through  1132  cubic 
foet  of  air. 

If  a  pound  of  rain-water  contain  only  ^th  of  a  grain  of  am- 
monki,  then  a  field  of  26,910  square  feet  must  receive  annually 


44  SOURCE  AND  ASSIMILATION  OF  NITROGEN. 


upwards  of  80  lbs.  of  ammon.ia,  or  65  lbs.  of  nitrogen;  for  by 
the  observations  of  Schubb  r,  formerly  alluded  to,  the  annual  fall 
must  be  about  2,520,000  lbs.  This  is  much  more  nitrogen  than 
is  contained  in  the  form  of  vegetable  albumen  and  gluten,  in 
2,650  lbs.  of  wood,  2,500  lbs.  of  hay,  or  200  cwt.  of  beet-root, 
which  are  the  yearly  produce  of  such  a  field  ;  but  it  is  less  than 
the  straw,  roots,  and  grain  of  corn,  which  might  grow  on  the 
same  surface,  would  contain. 

Experiments  made  in  this  laboratory  (Giessen)  with  the  great- 
est care  and  exactness,  have  placed  the  presence  of  ammonia  in 
rain-water  beyond  all  doubt.  It  has  hitherto  escaped  obser- 
vation, because  it  was  not  searched  for.  All  the  rain-water  em- 
ployed in  this  inquiry  was  collected  600  paces  south-west  of 
Giessen,  whilst  the  wind  was  blowing  in  the  direction  of  the 
town.  When  several  hundred  pounds  of  it  were  distilled  in  a 
copper  still,  and  the  first  two  or  three  pounds  evaporated  with  the 
addition  of  a  little  muriatic  acid,  a  very  distinct  crystallization 
of  sal-ammoniac  was  obtained  :  the  crystals  had  always  a  brown 
or  yellow  color. 

Ammonia  may  likewise  be  always  detected  in  snow-water. 
Crystals  of  sal-ammoniac  were  obtained  by  evaporating  in  a  ves- 
sel with  muriatic  acid  several  pounds  of  snow,  which  were  ga- 
thered from  the  surface  of  the  ground  in  March,  when  the  snow 
had  a  depth  of  ten  inches.  Ammonia  was  set  free  from  these 
crystals  by  the  addition  of  hydrate  of  lime.  The  inferior  layers 
of  snow  resting  upon  the  ground  contained  a  quantity  decidedly 
greater  than  those  upon  the  surface. 

It  is  worthy  of  observation  that  the  ammonia  contained  in  rain 
and  snow-water  possesses  an  otfensive  smell  of  perspiration  and 
putrefying  matter, — a  fact  which  leaves  no  doubt  respecting  its 
origin. 

Hunefield  has  proved  that  all  the  springs  in  Greifswalde,  Wiek, 
Eldena,  and  Kostenhagen,  contain  carbonate  and  nitrate  of  am- 
monia. Ammoniacal  salts  have  been  discovered  in  many  m'neral 
springs  in  Kissingen  and  other  places.  The  ammonia  of  these 
salts  can  only  arise  from  the  atmosphere.* 

•  Pharmaceutical  chemists  are  well  aware  of  the  existence  of  ammonU 


EXISTENCE  OF  AMMONIA  IN  THE  JUICES  OF  PLANTS.    45 

Any  one  may  satisfy  himself  of  the  presence  of  ammonia  in 
rain  by  simply  adding  a  little  sulphuric  or  muriatic  acid  to  a 
quantity  of  rain-water,  and  by  evaporating  this  nearly  to  dryness 
in  a  clean  porcelain  basin.  The  ammonia  remains  in  the  residue, 
in  combination  with  the  acid  employed  ;  and  may  be  detected 
either  by  the  addition  of  a  little  chloride  of  platinum,  or,  more 
simply,  by  a  little  powdered  lime,  which  separates  the  ammonia; 
and  thus  renders  sensible  its  peculiar  pungent  smell.  The  sen- 
sation  perceived  upon  moistening  the  hand  with  rain-water,  so 
different  from  that  produced  by  pure  distilled  water,  and  to  which 
the  term  softness  is  vulgarly  applied,  is  also  due  to  trie  carbonate 
of  ammonia  contained  in  the  former. 

The  ammonia  removed  from  the  atmosphere  by  rain  and  other 
causes,  is  as  constantly  replaced  by  putrefaction  of  animal  and 
and  vegetable  matters.*  A  certain  portion  of  that  which  falls 
with  the  rain  evaporates  again  with  the  water ;  but  another  por- 
tion is,  we  suppose,  taken  up  by  the  roots  of  plants,  and  entering 
into  new  combinations  in  the  different  organs  of  assimilation, 
produces,  by  the  action  of  these  and  of  certain  other  conditions, 
albumen,  gluten,  and  vegetable  casein,  or  quinine,  morphia, 
cyanogen,  and  a  numberof  other  compounds  containing  nitrogen. 
The  chemical  characters  of  ammonia  render  it  capable  of  enter- 
ing into  such  combinations,  and  of  undergoing  numerous  trans- 
formations. We  have  now  only  to  consider  whether  it  really  is 
taken  up  in  the  form  of  ammonia  by  the  roots  of  plants,  and  in 
that  form  applied  by  their  organs  to  the  production  of  the  azotised 
matters  contained  in  them.  This  question  is  susceptible  of  easy 
solution  by  well-known  facts. 

In  the  year  1834,  I  was  engaged  with  Dr.  Wilbrand,  professor 
)f  botany  in  the  University  of  Giessen,  in  an  investigation  re- 
in well-water,  for  they  have  often  to  reject  as  much  as  one-fourth  of  the 
water  distilled,  before  they  procure  water  which  is  not  rendered  turbid  by 
corrosive  sublimate.  But  when  phosphoric  acid  or  alum  is  added  to  the 
water  previous  to  distillation,  the  product  of  the  distillation  is  not  affected 
either  by  corrosive  sublimate  or  by  sugar  of  lead.  (Wiegmann  and  Pot- 
KTORr's  Prize  Essay  on  the  Inorganic  Ingredients  of  Plants.) 

*  "  We  cannot  doubt,"  says  Saussure,  "  that  ammonia  exists  in  the  atmo- 
sphere, for  we  know  that  sulphate  of  alumina  is  gradually  converted  int< 
•mmoniacal  alum  by  exposure  to  the  air  "     {Rech.  svr  la  Vigit.) 


49  SOURCE  AND  ASSIMILATION  OF  NITROGEN. 


specting  the  quantity  of  sugar  contained  in  different  varieties  of 
maple-trees,  growing  upon  unmanured  soils.  We  obtained  crys- 
tallized  sugars  from  all,  by  simply  evaporating  their  juices,  with- 
out the  addition  of  any  foreign  substance ;  and  we  unexpectedly 
made  the  observation,  that  a  great  quantity  of  ammonia  was  emit- 
ted from  this  juice  when  mixed  with  lime,  in  the  process  of  refin- 
ing, as  practised  with  cane  sugar.  The  vessels  which  hung  upon 
the  trees  in  order  to  collect  the  juice  were  watched  with  the 
greatest  attention,  on  account  of  the  suspicion  that  some  evil-dis- 
posed persons  had  introduced  urine  into  them,  but  still  a  large 
quantity  of  ammonia  was  again  found  in  the  form  of  neutral  salts. 
The  juice  had  no  color,  and  had  no  reaction  on  that  of  vegeta- 
bles.. Similar  observations  were  made  upon  the  juice  of  the 
birch  tree  ;  the  specimens  subjected  to  experiment  were  taken 
from  a  wood  several  miles  distant  from  any  house,  and  yet  the 
clarified  juice,  evaporated  with  lime,  emitted  a  strong  odor  of 
ammonia. 

In  the  manufactories  of  beet-root  sugar,  many  thousand  cubic 
feet  of  juice  are  daily  purified  with  lime,  in  order  to  free  it  from 
vegetable  albumen  and  gluten,  and  it  is  afterwards  evaporated 
for  crystallization.  Every  person  who  has  entered  such  a  manu- 
factory must  have  been  astonished  at  the  great  quantity  of  am- 
monia volatilized  along  with  the  steam.  This  ammonia  must  be 
contained  in  the  form  of  an  ammoniacal  salt,  because  the  neutral 
juice  possesses  the  same  characters  as  the  solution  of  such  a  salt 
in  water ;  it  acquires,  namely,  an  acid  reaction  during  evapora- 
tion, in  consequence  of  the  neutral  salt  being  converted  by  loss 
of  ammonia  into  an  acid  salt.  The  free  acid  thus  formed  is  a 
source  of  loss  to  the  manufacturers  of  sugar  from  beet-root,  by 
changing  a  part  of  the  sugar  into  uncrystallizable  grape  sugar 
and  syrup. 

The  products  of  the  distillation  of  flowers,  herbs,  and  roots, 
with  water,  and  all  extracts  of  plants  made  for  medicinal  pur- 
poses, contain  ammonia.  The  unripe,  transparent,  and  gelatinous 
pulp  of  the  almond  and  peach,  emit  much  ammonia  when  treated 
with  alkalies.  (Robiquet.)  The  juice  of  the  fresh  tobacco  leaf 
contains  ammoniacal  salts.  The  water  which  exudes  from  a  cut 
vine',  when  evaporated  with  a  few  drops  of  muriatic  acid,  also 


COMPOSITION  OF  EXCREMENTxTIOUS  MATTER.  4T 

yields  a  gummy  deliquescent  mass,  which  evolves  much  ammo, 
nia  on  the  addition  of  lime.  Ammonia  exists  in  every  part  of 
plants,  in  the  roots  (as  in  beet-root),  in  the  stem*  (of  the  maple, 
tree),  and  in  all  blossoms  and  fruit  in  an  unripe  condition. 

The  juices  of  the  maple  and  birch  contain  both  sugar  and  am- 
monia, and  therefore  afford  all  the  conditions  necessary  for  the 
formation  of  the  azotised  components  of  the  branches,  blossoms, 
and  leaves,  as  well  as  of  those  which  contain  no  nitrogen.  In 
proportion  as  the  development  of  those  parts  advances,  the  am- 
monia diminishes  in  quantity,  and  when  they  are  fully  formed, 
the  tree  yields  no  more  juice. 

The  employment  of  animal  manure  in  the  cultivation  of  grain, 
and  the  vegetables  which  serve  for  fodder  to  cattle,  is  the  most 
convincing  proof  that  the  nitrogen  of  vegetables  is  derived  from 
ammonia.  The  quantity  of  gluten  in  wheat,  rye,  and  barley,  is 
very  variable  ;  these  kinds  of  grain  also,  even  when  ripe,  con- 
tain this  compound  of  nitrogen  in  very  different  proportions. 
Proust  found  French  wheat  to  contain  12-5  per  cent,  of  gluten  ; 
Vogel  found  that  the  Bavarian  contained  24  per  cent. ;  Davy 
obtained  19  per  cent,  from  winter,  and  24  from  summer  wheat ; 
from  Sicilian  21,  and  from  Barbary  wheat  19  per  cent.  The 
flour  of  Alsace  wheat  contains,  according  to  Boussingault,  17*3 
per  cent,  of  gluten ;  that  of  wheat  grown  in  the  "  Jardin  des 
Plantes,"  26-7  ;  and  that  of  winter  wheat,  33-3  per  cent.  Such 
great  differences  must  be  owing  to  some  cause,  and  this  we  find 
in  the  different  methods  of  cultivation.  An  increase  of  animal 
manure  gives  rise  not  only  to  an  increase  in  the  number  of  seeds, 
but  also  to  a  niost  remarkable  difference  in  the  proportion  of  the 
substances  contaming  nitrogen,  such  as  the  gluten. 

Animal  manure  exerts  a  very  complex  action  on  plants,  but  as 
far  as  regards  the  assimilation  of  nitrogen,  it  acts  only  by  the 
formation  of  ammonia.  One  hundred  parts  of  wheat  grown  on 
a  soil  manured  with  cow-dung  (a  manure  containing  the  smallest 
quantity  of  nitrogen),  afforded  only  11-95  parts  of  gluten,  and 
62*34    parts   of  amy] in,  or  starch ;  whilst   the  same   quantity, 

•  In  an  experiment  performed  at  my  reqnp«»t  in  Calcutta,  it  was  found 
that  the  fresh  juice  of  the  palm  tree  abounded  with  ammonia, — Ed. 


is  SOURCE  AND  ASSIMILATION  OF  NIGROGEN. 

grown  on  a  soil  manured  with  human  urine,  yielded  the  maxi- 
mum of  gluten,  namely  35-1  percent.,  or  nearly  three  times  the 
quantity.  Putrefied  urine  contains  nitrogen  in  the  forms  of 
carbonate,  phosphate,  and  muriate  of  ammonia,  and  in  no  other 
form  than  that  of  ammoniacal  salts. 

Putrid  urine  is  employed  in  Flanders  as  a  manure,  with  the 
best  results.  During  the  putrefaction  of  urine,  ammoniacal  salts 
are  formed  in  large  quantity,  it  may  be  said  exclusively  ;  for 
under  the  influence  of  heat  and  moisture,  urea,  the  most  promi- 
nent ingredient  of  the  urine,  is  converted  into  carbonate  of  am- 
monia. The  barren  soil  on  the  coast  of  Peru  is  rendered  fertile 
by  means  of  a  manure  called  Guano,  which  is  collected  from 
several  Islands  in  the  South  Sea.*  It  is  sufficient  to  add  a  small 
quantity  of  guano  to  a  soil  consisting  only  of  sand  and  clay,  in 
order  to  procure  the  richest  crop  of  maize.  The  soil  itself  dops 
not  contain  the  smallest  particle  of  organic  matter,  and  the  ma- 
nure employed  is  formed  only  of  urate,  phospJiaie,  oxalate^  and 
carbonate  of  ammonia,  together  with  salts. "j" 

The  ammonia,  therefore,  pf  the  salts  contained  in  Guano,  must 
have  yielded  the  nitrogen  to  th6se  plants.  Gluten  is  obtained 
from  corn  ;  vegetable  albumen  from  certain  juices,  such  as  from 
the  expressed  juice  of  the  grape  ;  vegetable  casein  occurs  in  the 
seeds  of  the  leguminous  plants  ;  but  although  all  these  have  dif- 
ferent names  and  properties,  they  are  identical  in  composition 
with  the  ordinary  gluten. 

It  is  then  ammonia  which  yields  nitrogen  to  the  vegetable  albu- 
men, the  principal  azotised  constituent  of  plants.  Nitrogen  is 
not  presented  to  wild  plants  in  any  other  form  capable  af  assimi- 
lation. Ammonia,  by  its  transformation,  furnishes  nitric  acid  to 
the  tobacco-plant,  sunflower,  Chenopodium,  and  Borago  officinalis, 
when  they  grow  in  a  soil  completely  free  from  nitre.  Nitrates 
are  necessary  constituents  of  these  plants,  which  thrive  only 
when  ammonia  is  present  in  large  quantity,  and  when  they  are 

*  The  guano,  which  forms  a  stratum  several  feet  in  thickness  upon  the 
surface  of  these  islands,  consists  of  the  putrid  excrements  of  innumerable 
•ea  fowl  that  remain  on  them  during  the  breeding  season.  (See  tb# 
Chapter  on  Manures.) 

t  Boussingault,  Ann.  de  Ch.  et  de  Phys.,  Ixv.,  p.  3H) 


FORM  IN  WHICH  AMMONIA  IS  PRESENTED.  49 


also  subject  to  the  influence  of  the  direct  rays  of  the  sun  ;  an 
nfluence  necessary  to  effect  the  disengagement  within  their  slem 
and  leaves  of  the  oxygen  which  shall  unite  with  the  ammonia  to 
form  nitric  acid. 

The  urine  of  men  and  of  carnivorous  animals  contains  the 
largest  quantity  of  nitrogen,  partly  in  the  form  of  phosphates, 
partly  as  urea.  Urea  is  converted  during  putrefiiction  into  car- 
bonate of  ammonia,  that  is  to  say,  it  takes  the  form  of  the  very 
salt  in  rain-water.  Human  urine  is  the  most  powerful  manure 
for  vegetables  rich  in  nitrogen  ;  the  urine  of  cattle,  sheep,  and 
horses,  contains  less  nitrogen  ;  but  yet  far  more  than  the  solid 
excrements  of  these  animals.  In  addition  to  urea,  the  urine  of 
herbivoKous  animals  contains  hippuric  acid,  which  is  decomposed 
during  putrefiiction  into  benzoic  acid,  and  ammonia.  The  latter 
causes  the  formation  of  gluten,  but  the  benzoic  acid  oflen  remains 
unchanged  :  for  example,  in  tlie  Anthoxanikum  odoratum. 

The  solid  excrements  of  men  and  of  animals  contain  compara- 
tively very  little  nitrogen,  but  this  could  not  be  otherwise.  The 
food  taken  by  animals  supports  them  only  in  so  far  as  it  offers  to 
the  various  organs  elements  for  assimilation  which  they  may 
require  for  their  increase  or  renewal.  Corn,  grass,  hay,  and  all 
plants,  without  exception,  whether  fresh  or  dried,  contain  highly 
azotised  substances.  The  quantity  of  food  n  quired  by  animals 
for  their  nourishment  diminishes  or  increases  in  the  same  propor- 
tion as  it  contains  more  or  less  of  the  substances  containing 
nitrogen.  A  horse  may  be  kept  alive  by  feeding  it  with 
potatoes,  a  food  containing  a  very  small  quantity  of  nitrogen  ; 
but  life  thus  supported  is  i\  gradual  starvation  ;  the  animal 
increases  neither  in  size  nor  strength,  and  sinks  under  every 
exertion.  The  quantity  of  rice  consumed  by  an  Indian  astonishes 
the  European  ;  but  the  fact  that  rice  contains  less  nitrogen  than 
any  other  kind  of  grain  at  once  explains  the  circumstance. 

Now,  as  it  is  evident  that  the  nitrogen  of  the  plants  and  seeds 
used  by  animals  as  food  must  be  employed  in  the  process  of 
assimilation,  it  is  natural  to  expect  that  the  solid  excrements  of 
these  animals  will  be  deprived  of  it  in  proportion  to  the  perfect 
digestion  of  the  food,  and  can  only  contain  it  when  mixed  with 
secretions  from  the  liver  and  intestines.  Under  all  rircumstan. 
4 


50  SOURCE  AND  ASSIMIL-\T10N  OF  NITROGEN. 

ces,  they  must  contain  less  nitrogen  than  the  food.  When, 
therefore,  a  field  is  manured  with  animal  excrements,  a  smaller 
quantity  of  matter  containing  nitrogen  is  added  to  it  than  has 
been  taken  from  it  in  the  form  of  grass,  herbs,  or  seeds.  There- 
fore, it  follows  that  the  favorable  activity  of  such  manure  cannot 
be  due  to  its  nitrogen. 

The  liquid  manure  of  animals  must,  on  the  other  hand,  be  of 
the  highest  value  with  respect  to  nitrogen :  because  it  contains 
all  or  nearly  all  the  nitrogen  originally  present  in  the  food  con- 
sumed. In  order  to  comprehend  more  clearly  the  importance 
of  liquid  excrements,  it  is  necessary  to  consider  the  manner  in 
which  they  are  formed. 

It  is  well  known  that  the  body  of  an  adult  man,  or  of  ah  animal 
in  a  state  of  health,  remains  constantly  the  same,  and  neither 
diminishes  nor  increases  in  weight  to  any  appreciable  extent. 
In  youth  the  case  ii  different ;  for  an  increase  of  the  body  is 
occasioned.  The  same  is  the  case  in  the  artificial  process  of 
fattening.  The  body  of  the  old  man,  on  the  other  hand,  gra- 
dually diminishes  in  size. 

The  quantity  of  nitrogen  and  of  other  constituents  in  the  body 
cannot  therefore  increase,  although  the  animal  always  receives 
in  his  food  a  considerable  quantity  of  that  element.  From  this 
it  follows,  that  the  quantity  of  nitrogen  expelled  from  the  body 
must  be  the  same  as  that  taken  in  the  food  by  an  animal  in  a 
state  of  nature,  freely  exposed  to  exercise  ;  for  if  this  were  not 
the  case,  the  body  must  acquire  a  larger  proportion  of  nitrogen, 
which  we  know  it  does  not. 

When  an  individual  is  deprived  of  food  and  in  the  progress  of 
starvation,  his  body  diminishes  in  weight,  in  Such  a  manner  that 
all  parts,  except  the  membranes  and  bones,  participate  in  the 
loss.  By  what  means  has  the  nitrogen  of  those  tissues  been 
expelled  from  the  system  ? 

The  emaciation  which  occurs  proves  that  during  every  moment 
in  the  life  of  an  animal,  part  of  its  structure  loses  its  vitality,  and 
assumes  the  form  of  dead  matter.  This,  after  suffering  certain 
changes,  is  finally  separated  from  the  system  by  the  organs  of 
secretion,  namely,  the  skin,  lungs,  and  kidneys.  The  daily  losi 
thus  experienced  is  restored  by  food. 


FORM  IN  WHICH  AMMONIA  IS  PRESENTED.  51 

The  azotised  constituents  of  the  food  are  transformed  into 
blood,  which  then  nourishes  the  animal  by  restoring  its  wasten 
tissues  to  their  original  condition. 

The  uniform  weight  of  an  animal  proves  that  a  quan- 
tity OF  NITROGEN  MUST  HAVE  BEEN  EXPELLED  FROM  THE  SYSTEM, 
EXACTLY    CORRESPONDING  TO  THE  AMOUNT   CONTAINED   IN  THE  FOOD 

CONSUMED.  The  compounds  consisting  of  carbon  and  hydrogen, 
derived  from  the  waste  matter,  are  separated  by  the  lungs  and 
skin  ;  whilst  those  containing  nitrogen  are  eliminated  in  the 
urine.  When  the  body  increases  in  weight,  a  smaller  quantity 
of  nitrogenous  compounds  must  be  separated  by  the  urine  ;  a 
diminution  in  weight  indicates,  on  the  other  hand,  a  greater 
separation  of  these  compounds.  These  considerations  prove  that 
the  nitrogen  extracted  from  the  atmosphere  by  plants  as  food,  is 
again  in  a  great  measure  returned  in  the  urine  of  man  and  other 
animals. 

It  is  obvious  that,  by  collecting  both  the  solid  and  liquid  excre- 
ments of  an  animal  fed  upon  the  produce  of  a  certain  surface  of 
land,  we  are  enabled  to  supply  to  it  nearly  the  same  quantity  of 
nitrogen  as  that  contained  in  the  original  produce.  Thus  we 
supply  to  the  land  a  certain  quantity  of  ammonia,  in  addition  to 
that  which  may  be  extracted  from  the  atmosphere  by  the  plants 
growing  upon  it. 

In  a  scientific  point  of  view,  it  should  be  the  care  of  the  agri- 
culturist so  to  employ  all  the  substances  containing  a  large  pro- 
portion of  nitrogen,  which  his  farm  affords  in  the  form  of  animal 
excrements,  that  they  shall  serve  as  nutriment  to  his  own  plants. 
This  will  not  be  the  case  unless  those  substances  are  properly 
distributed  upon  his  land.  A  heap  of  manure  lying  unemployed 
upon  his  land  would  serve  him  no  more  than  his  neighbors.  The 
nitrogen  in  it  would  escape  as  carbonate  of  ammonia  into  the 
atmosphere,  and  a  mere  carbonaceous  residue  of  decayed  plants 
would,  after  some  years,  be  found  in  its  place. 

Tacitus  informs  us  that  the  surface  of  Germany  was  in  his 
time  completely  covered  with  impenetrable  forests.  But  now 
these  no  longer  exist,  and  all  their  constituents  have  disappeared. 
The  carbon  and  nitrogen  deposited  in  the  soil  in  the  form  of 
humus  and  ammonia  have  now  returned  to  the  atmosphere. 


63  SOURCE  AND  ASSIMILATION  OF  NITROGEN. 


All  putrefying  animal  matters  emit  carbonic  acid  and  ammonia 
as  long  as  nitrogen  exists  in  them.  In  every  stage  of  their  putre- 
faction an  escape  of  ammonia  from  them  may  be  induced  by 
moistening  them  with  a  potash  ley  ;  the  ammonia  being  apparent 
to  the  senses  by  a  peculiar  smell,  and  by  the  dense  white  vapor 
exhibited  when  a  solid  body  moistened  with  an  acid  is  brought 
near  it.  This  ammonia  evolved  from  manure  is  imbibed  by  the 
soil  either  in  solution  in  water,  or  in  the  gaseous  form,  and  plants 
thus  receive  a  larger  supply  of  nitrogen  than  is  afforded  to  them 
by  the  atmosphere.* 

But  it  is  much  less  the  quantity  of  ammonia  yielded  to  a  soil 
by  animal  excrements,  than  the  form  in  which  it  is  presented  by 
them,  that  causes  their  great  influence  on  its  fertility.  Wild 
plants  obtain  more  nitrogen  from  the  atmosphere  in  the  form  of 
ammonia  than  they  require  for  their  growth  ;  for  the  water 
evaporated  through  their  leaves  and  blossoms  emits,  after  some 
time,  a  putrid  smell,  a  peculiarity  possessed  only  by  bodies  con- 
taining nitrogen.  Cultivated  plants  receive  the  same  quantity  of 
nitrogen  from  the  atmosphere  as  trees,   shrubs,  and  other  wild 

*  "  I  filled  a  large  retort,"  says  Sir  H.  Davy,  "  capable  of  containing 
three  pints  of  water,  with  some  hot  fermenting  manure,  consisting  prin- 
cipally of  the  litter  and  dung  of  cattle  ;  and  adapted  a  small  receiver  to 
the  retort,  and  connected  the  whole  with  a  mercurial  pneumatic  appa- 
ratus, so  as  to  collect  the  condensible  and  elastic  fluids  which  might  rise 
from  tb«»  dung.  The  receiver  soon  became  lined  with  dew,  and  drops 
began  in  a  few  hours  to  trickle  down  the  sides  of  it.  Elastic  fluid  like- 
wise was  generated  ;  in  three  days  35  cubical  inches  had  been  formed, 
which,  when  analysed,  were  found  to  contain  21  cubical  inches  of  car- 
bonic acid ;  the  remainder  was  hydro-carbonate  mixed  with  some  azote, 
probably  no  more  than  existed  in  the  common  air  in  the  receiver.  The 
fluid  matter  collected  in  the  receiver  at  the  same  time  amounted  to 
nearly  half  an  ounce.      It  had  a  saline  taste,    and  a  disagreeable  smell, 

nd  contained  some  acetate  and  carbon^ate  of  ammonia. 
"  Finding  such  products  given  off"  from  fermenting  litter,  I  introduced 

he  beak  of  another  retort,  filled  with  similar  dung  very  hot  at  the 
Vime,  into  the  soil  amongst  the  roots  of  some  grass  in  the  border  of  a 
garden  ;  in  less  than  a  week  a  very  distinct  effect  was  produced  on  the 
grass ;  upon  the  spot  exposed  to  the  influence  of  the  matter  disengaged 
in  fermentation,  it  grew  with  more  luxuriance  than  the  grass  in  any 
other  part  of  the  garden." — Works  of  Sir  H.  Davy,  Edited  by  Dr.  Johu 
Davy,  vol.  viii.,  page  31 


USE  OF  GYPSUM.  53 

plants ;  and  this  is  quite  sufficient  for  the  purposes  of  agricuL 
ture.  Agriculture  differs  essentially  from  the  cultivation  of 
forests,  inasmuch  as  its  principal  object  consists  in  the  production 
of  THE  CONSTITUENTS  OF  THE  BLOOD  ;  whilst  the  object  of  forest 
culture  is  confined  principally  to  the  production  of  carbon.  But 
the  presence  of  ammonia  alone  does  not  suffice  for  the  production 
of  the  nitrogenous  ingredients.  Other  conditions  likewise  are 
quite  essential.  All  the  various  means  of  culture  are  sub- 
servient to  these  two  main  purposes.  A  part  only  of  the  car 
bonate  of  ammonia  conveyed  by  rain  to  the  soil  is  received  by 
plants,  because  a  certain  quantity  of  it  is  volatilized  with  the 
vapor  of  water ;  only  that  portion  of  it  can  be  assimilated  which 
sinks  deeply  into  the  soil,  or  which  is  conveyed  directly  to  the 
leaves  by  dew,  or  is  absorbed  from  the  air  along  with  the 
carbonic  acid. 

I^iquid  animal  excrements,  such  as  the  urine  with  which  the 
solid  excrements  are  impregnated,  contain  only  a  small  part  of 
their  ammonia  in  the  state  of  salts,  that  is,  in  a  form  in  which  it 
has  completely  lost  its  volatility.  The  greatest  part  exists  in  the 
form  of  carbonate  of  ammonia — a  salt  of  great  volatility.  When 
the  ammonia  is  presented  in  the  condition  of  a  fixed  salt,  not  the 
smallest  portion  of  it  is  lost  to  plants  ;  it  is  all  dissolved  by  water, 
and  imbibed  by  their  roots.  The  evident  influence  of  gypsum 
upon  the  growth  of  grasses — the  striking  fertility  and  luxuriance 
of  a  meadow  upon  which  it  is  strewed — depends,  in  some  degree, 
upon  its  fixing  in  the  soil  the  ammonia  of  the  atmosphere,  which 
would  otherwise  be  volatilized,  with  the  water  which  evaporates.* 

*  I  made  the  following  experiment  on  a  small  g^arden  plot.  Beans  and 
peas  were  planted  in  the  soil,  after  it  had  been  well  manured  by  mixing  it 
with  fresh  horse-dung.  The  whole  surface  of  the  plot  was  strewed  with 
gypsum  to  the  depth  of  a  line,  and  then  covered  so  as  to  be  protected  from 
the  rain.     In  dry  weather  it  was  duly  watered. 

The  plants  soon  appeared  above  grouiid  and  flourished  with  great  luxuri- 
ance. Before  the  commencement  of  the  experiment,  I  had  examined  both 
the  soil  and  the  gypsum,  and  found  that  both  were  quite  free  from  the 
smallest  trace  of  carbonates.  But  on  testing  some  of  the  gypsum  taken 
from  the  surface  after  the  lapse  of  several  weeks,  I  ascertained  that  the 
greatest  part  of  it  had  been  converted  into  carbonate  of  lime.  All  th« 
soil  to  the  depth  of  half  a  foot  now  effervesced  strongly  on  the  addition  of 
acid. 


84  SOURCE  AND  ASSIMILATION  OF  NITROGEN. 


The  carbonate  of  ammonia  contained  in  rain-water  is  decomposed 
by  gypsum,  in  precisely  the  same  manner  as  in  the  manufacture 
of  sal  ammoniac.  Soluble  sulphate  of  ammonia  and  carbonate 
of  lime  are  formed  ;  and  this  salt  of  ammonia,  possessing  no 
volatility,  is  consequently  retained  in  the  soil.  All  the  gypsum 
gradually  disappears,  but  its  action  upon  the  carbonate  of  ammo- 
nia continues  as  long  as  a  trace  of  it  exists.* 

The  beneficial  influence  of  gypsum  and  of  many  other  salts 
has  been  compared  to  that  of  aromatics,  which  increase  the 
activity  of  the  human  stomach  and  intestines,  and  give  a  tone 
to  the  whole  system.  But  plants  do  not  contain  nerves  :  we 
know  of  no  substance  capable  of  exciting  them  to  intoxication 
and  madness,  or  of  lulling  them  to  sleep  and  repose.  No  sub- 
stance can  possibly  cause  their  leaves  to  appropriate  a  greater 
quantity  of  carbon  from  the  atmosphere,  when  the  other  constitu- 
ents required  for  the  growth  of  the  seeds,  roots,  and  leaves,  are 
wanting. f  The  favorable  action  of  small  quantities  of  aromatics 
upon  man,  when  mixed  with  his  food,  is  undeniable ;  but  aro- 
matics  are  given  to  plants  without  food  to  be  digested,  and  still 
they  flourish  with  greater  luxuriance. 

It  is  quite  evident,  therefore,  that  the  common  view  concerning 
the  influence  of  certain  salts  upon  the  growth  of  plants  evinces 
only  ignorance  of  its  cause. 

The  action  of  gypsum,  chloride  of  calcium,  and  of  other  salts 
of  lime,  really  consists  in  their  giving  a  fixed  condition  to  the 
nitrogen,  or  ammonia,  introduced  to  the  soil.  This  nitrogen,  is 
indispensable  for  the  nutrition  of  plants. 

In  order  to  form  a  conception  of  the  effect  of  gypsum,  it  may 
be  sufl[icient  to  remark  that  100  lbs.  of  burned  gypsum  fixes  as 

*  It  has  long  been  the  practice  in  some  parts  of  the  country  to  strew 
the  floors  of  stables  with  gypsum.  This  prevents  the  disagreeable  odor 
arising  from  the  putrefaction  of  stable  manure,  by  decomposing  and  re- 
taining the  ammoniacal  salts. — Ed, 

"  I  lixiviated  some  earth,"  says  Spatzier,  "  and  in  the  filtered  solution, 
after  evaporation,  I  obtained  an  appreciable  quantity  of  sulphate  of  ammo- 
nia."— Erdmari's  Journal,  1831,  Bd   II  ,  s.  89. 

f  Schiibler  states  that  white  arsenic  in  small  quantity  exerts  a  beneficial 
action  upon  vegetation — a  fact  proved  by  Lampadius,  who  manured  whole 
fields  with  this  substance. 


USE  OF  BURNED  CLAY  AS  A  MANURE.  55 


much  ammonia  in  the  soil  as  0250  lbs.  of  horse's  urine*  would 
yield  to  it,  even  on  the  supposition  that  all  the  nitrogen  of  the 
urea  and  hippuric  acid  were  absorbed  by  the  plants  without  the 
smallest  loss,  in  the  form  of  carbonate  of  ammonia.  If  we 
furnish  to  a  field  40  lbs.  of  gypsum,  and  if  we  suppose  that  the 
tenth  part  of  this  enters  into  plants  in  the  form  of  sulphate  of 
ammonia,  we  would  actually  supply  nitrogen  sufficient  for  100 
lbs.  of  hay,  50  lbs.  of  wheat,  or  60  lbs.  of  clover. 

Water  is  absolutely  necessary  to  effect  the  decomposition  of 
the  gypsum,  on  account  of  its  difficult  solubility  (1  part  of  gyp- 
sum requires  400  parts  of  water  for  solution),  and  also  to  assist 
in  the  absorption  of  the  sulphate  of  ammonia  by  the  plants : 
hence  it  happens,  that  the  influence  of  gypsum  is  not  observable 
on  dry  fields  and  meadows  ;  wlii'e  the  gaseous  carbonate  of 
ammonia  formed  by  the  decay  of  animal  manures  on  such  fields, 
on  the  other  hand,  does  not  fail  in  producing  a  favorable  effect. 

The  decomposition  of  gypsum  by  carbonate  of  ammonia  does 
not  take  place  instantaneously  ;  on  the  contrary,  it  proceeds  very 
gradually  ;  and  this  explains  why  the  action  of  the  gypsum  lasts 
for  several  years. 

The  well-known  advantage  derived  by  manuring  fields  with 
burnt  clay,  and  the  fertility  of  ferruginous  soils,  may  be  ex- 
plained in  an  equally  simple  manner.  The  favorable  effects 
produced  by  these  causes  have  been  ascribed  to  the  great  attrac- 
tion for  water  exerted  by  dry  clay  and  ferruginous  earth  ;  but 
common  dry  arable  land  possesses  this  property  in  as  great  a 
degree  ;  and  besides,  what  influence  can  be  ascribed  to  a  hun- 
dred pounds  of  water  spread  over  a  field,  in  a  condition  in  which 
it  cannot  be  made  available  either  by  the  roots  or  leaves  ?  The 
true  cause  is  this  : — 

Peroxide  of  iron  and  alumina  are  distinguished  from  all  other 
metallic  oxides  by  their  power  of  forming  solid  compounds  with 

*  The  urine  of  the  horse  contains,  according  to  Fourcroy  and  Vauquelin, 
in  lOO)  parts. 

Urea       .         .  .  7  parts. 

Hippurate  of  soda     .  14    ** 

Salts  and  water  .         979     " 

1 000  parts.    (  See  Appendix. ) 


56  SOURCE  AND  ASSIMILATION  OF  NITROGEN. 


ammonia.  The  precipitates  obtained  by  the  addition  of  ammonia 
to  salts  of  alumina  or  iron  are  true  salts,  in  which  the  ammonia 
is  contained  as  a  base.  Minerals  containing  alumina  or  oxide 
of  iron  also  possess,  in  an  eminent  degree,  the  remarkable  property 
of  attracting  ammonia  from  the  atmosphere  and  of  retaining  it. 
Vauquelin,  whilst  engaged  in  the  trial  of  a  criminal  case,  dis- 
covered that  all  rust  of  iron  contains  a  certain  quantity  of 
ammonia.  Chevalier  afterwards  found  that  ammonia  is  a  con- 
stituent of  all  minerals  containing  iron  ;  that  even  hematite,  a 
mineral  which  is  not  at  all  porous,  contains  one  per  cent,  of  it. 
Bouis  showed  also  that  the  peculiar  odor  observed  on  moistening 
minerals  containing  alumina,  is  partly  owing  to  their  exhaling 
ammonia.  Indeed,  many  kinds  of  gypsum  and  some  varieties 
of  alumina,  pipe-clay  for  extrnple,  emit  so  much  ammonia,  when 
moistened  with  caustic  potash,  even  after  they  have  been  exposed 
for  two  days,  that  reddened  litmus  paper  held  over  them  becomes 
blue.  Soils,  therefore,  containing  oxides  of  iron,  and  burned 
clay,  must  absorb  ammonia,  an  action  which  is  favored  by  their 
porous  condition  ;  they  further  prevent,  by  their  chemical  pro- 
perties, the  escape  of  the  ammonia  once  absorbed.  Such  soils, 
in  fact,  act  precisely  as  a  mineral  acid  would  do,  if  extensively 
spread  over  tl)eir  surface. 

The  ammonia  absorbed  by  the  clay  of  ferruginous  oxides  is 
separated  by  every  shower  of  rain,  and  conveyed  in  solution  to 
the  soil. 

Powdered  charcoal  possesses  a  similar  action,  but  surpasses  all 
other  substances  in  the  power  which  it  possesses  of  condensing 
ammonia  within  its  pores,  particularly  when  it  has  been  previ- 
ously heated  to  redness.  Charcoal  absorbs  ninety  times  its 
volume  of  ammoniacal  gas,  which  may  be  again  separated  by 
simply  moistening  it  with  water.  (De  Saussure.)  Decayed 
wood  approaches  very  nearly  to  charcoal  in  this  power  ;  decayed 
oak  wood  absorbs  seventy-two  times  its  volume  of  this  gas,  after 
having  been  completely  dried  under  the  air-pump.  We  have 
here  an  easy  and  satisfactory  means  of  explaining  still  further 
the  properties  of  humus,  or  wood  in  a  decaying  state.  It  is  not 
only  a  slow  and  constant  source  of  carbonic  acid,  but  it  is  also 


CONCLUSION.  5? 


a   means   by    which    the    necessary    nitrogen   is   conveyed   to 
plants.* 

Nitrogen  is  found  in  lichens  growing  on  basaltic  rocks.  Our 
fields  produce  more  of  it  than  we  have  given  them  as  manure, 
and  it  exists  in  all  kinds  of  soils  and  minerals  which  were  never 
in  contact  with  organic  substances.  The  nitrogen  in  these  cases 
could  only  have  been  extracted  from  the  atmosphere. 

We  find  this  nitrogen  in  the  atmosphere,  in  rain-water,  and  in 
all  kinds  of  soils,  in  the  form  of  ammonia,  as  a  product  of  the 
decay  and  putrefaction  of  preceding  generations  of  animals  and 
vegetables.  We  find  likewise  that  the  proportion  of  azotised 
matters  in  plants  is  augmented  by  giving  them  a  larger  supply 
of  ammonia  conveyed  in  the  form  of  animal  manure. 

No  conclusion  can  then  have  a  better  foundation  than  this, 
that  it  is  the  ammonia  of  the  atmosphere  which  furnishes  nitro- 
gen to  plants. I 

Carbonic  acid,  water,  and  ammonia,  contain  the  elements 
necessary  for  the  support  of  animals  and  vegetables.  The  same 
substances  are  the  ultimate  products  of  tiie  chemical  processes 
of  decay  and  putrefaction.  All  the  innumerable  products  of 
vitality  resume,  after  death,  the  original  form  from  which  they 
sprung. 

Thus  the  destruction  of  an  existing  generation  becomes  the 
means  for  the  production  of  a  new  one,  and  death  becomes  the 
source  of  life. 

But  it  may  be  asked — Are  the  compounds  now  named  the 
only  substances  necessary- for  the  support  of  vegetable  life  ?  This 
question  must  be  answered  decidedly  in  the  negative. 

•  When  the  extract  of  humus  is  evaporated  with  muriatic  acid,  a  residue 
is  obtained  which  evolves  ammonia  by  the  addition  of  potash.  When  this 
extract  is  subjected  to  distillation  along  with  water,  and  the  products  of 
distillation  received  into  dilute  muriatic  acid,  the  latter  is  found  to  contain 
muriate  of  ammonia.  Humus  contains  carbonate  of  ammonia. —  Wieg- 
mann  und  Polstorfy  Priesschrift,  s.  53. 

t  We  refer  the  reader  to  the  Appendix  for  the  part  which  nitric  acid 
takes  in  vegetation,  and  also  for  the  origin  of  ammonia 
4* 


ON  THE  SOURCE  OF  SULPHUR. 


CHAPTER  VI. 

On  the  Source  of  Sulphur. 

Physiology  teaches  us  that  all  the  tissues  of  the  body,  such  as 
muscular  fibre,  cellular  tissue,  the  organic  substance  of  bones, 
hair,  skin,  &c.,  are  formed  from  the  blood — the  fluid  which  cir- 
culates through  every  part  of  the  organism. 

The  blood,  from  which  all  parts  of  the  animal  frame  are  pro- 
duced, is  itself  furnished  to  animals  by  plants.  For  although 
the  carnivora  subsist  wholly  on  the  flesh  and  blood  of  the  herbi- 
vora,  they  actually  receive  from  the  latter  the  component  parts 
of  the  plants  upon  which  they  were  nourished. 

Chemists  have  ascertained  that  sulphur  is  contained  in  the 
two  principal  ingredients  of  blood,  named  by  them  fibrin  and 

ALBUMEN. 

When  fresh  blood  is  agitated  with  a  rod  or  stick,  fibrin  is 
separated  in  the  form  of  white  elastic  fibres.  A  similar  separa- 
tion of  this  ingredient  takes  place  when  blood  is  allowed  to  stand 
for  a  certain  time.  The  whole  becomes  coagulated  into  a  sort  of 
jelly,  which  gradually  contracts,  and  separates  itself  into  a  yellow- 
ish-colored liquid,  containing  the  serum  or  water  of  the  blood,  and 
into  a  net- work  of  very  fine  threads  of  fibrin.  The  latter  inclose 
within  them  the  coloring  matter  of  the  blood,  just  as  a  sponge 
would  do  in  similar  circumstances. 

The  ALBUMEN  is  contained  in  the  serum,  and  communicates  to 
that  fluid  the  property  of  coagulating  by  heat,  in  a  manner 
similar  to  the  white  of  an  egg,  which  contains  albumen  as  its 
principal  ingredient. 

Fibrin,  when  removed  from  the  circulation,  is  found  to  be  per- 
fectly insoluble  in  cold  water.  Albumen  on  the  other  hand,  in 
its  natural  condition,  as  it  exists  in  serum  or  in  the  white  of  egg, 
is  soluble  in  water,  and  miscible  with  it  in  all  proportions. 


VEGETABLE  CONSTITUENTS  OF  BLOOD.  M 

Casein,  or  cheese,  the  principal  ingredient  of  milk,  must  also 
be  enumerated  as  a  material  used  in  the  formation  of  blood. 
Casein  is  generated  in  the  animal  economy,  and  is  the  only  azo« 
lised  nutriment  furnished  by  the  mother  to  the  young  animal. 

Now  albumen,  fibrin,  and  casein  contain  sulphur,  a  circum- 
stance by  which  they  are  distinguished  from  all  other  component 
parts  of  the  animal  body.  This  sulphur  does  not  exist  in  the 
form  of  an  oxide,  such  as  sulphuric  acid  or  one  of  its  salts.  It 
is^eTl' Known  tliaV  the  albumen  of  eggs  emits,  during  its  putre- 
faction, sulphuretted  hydrogen  gas  ;  and  it  is  owing  to  this  that 
rotten  eggs  possess  the  property  of  blackening  silver  or  other 
metals  with  which  they  may  be  brought  in  contact.  During  the 
putrefaction  of  fibrin  and  albumen,  the  same  gas  is  likewise  gene- 
rated. There  are  many  other  ways  by  which  we  might  prove 
the  presence  of  sulphur  in  these  bodies. 

From  what  source  does  the  animal  body  derive  these  three  fun- 
damental components  ?  Unquestionably  they  are  obtained  from 
the  plants  upon  which  the  animals  subsist :  but  in  what  form,  and 
in  what  condition,  are  they  contained  in  plants  ? 

Rccerrt  investigations  of  chemists  have  enabled  us  to  answer 
these  questions  with  positive  certainty.  Plants  contain,  either 
deposited  in  their  roots  or  seeds,  or  dissolved  in  their  juices, 
variable  quantities  of  compounds  containing  sulphur.  In  these 
nitrogen  is  an  invariable  constituent.  Two  of  the  compounds 
containing  sulphur  exist  in  the  seeds  of  cereal  plants,  and  in 
those  of  leguminous  vegetables,  such  as  peas,  lentils,  and  beans. 
A  third  is  always  present  in  the  juices  of  all  plants;  and  it  is 
found  in  the  greatest  abundance  in  the  juices  of  those  which  we 
use  for  the  purpose  of  the  table. 

A  very  exact  inquiry  into  the  properties  and  composition  of 
substances  has  produced  a  very  remarkable  result,  namely,  that 
the  sulphur  compound  dissolved  in  the  juice  of  plants  is,  in  re- 
ality, identical  with  the  albumen  contained  in  the  serum  of 
blood,  and  in  the  white  of  an  egg  ;  that  the  sulphur  compound  in 
the  seeds  of  the  cereals  possesses  the  same  properties  and  com- 
position as  the  FIBRIN  of  blood;  and  that  the  nutritious  constitu- 
ent of  peas,  beans,  ard  lentils,  is  actually  of  the  same  nature  and 
composition  as  the  casein  of  milk.     Hence  it  follows  that  plants, 


60  ON  THE  SOIJRCK  OF  SULPHUR. 


and  not  animals,  generate  the  constituents  of  blood  containing 
sulphur.  When  these  are  absent  from  the  food  given  to  an 
animal,  its  blood  cannot  be  formed.  From  this  it  also  follows, 
that  vegetable  food  will  be  proportionally  nutritious  and  fit  to 
sustain  tlie  vital  processes  of  the  animal  body,  according  to  the 
amount  of  these  ingredients  contained  within  it. 

There  also  exist  certain  families  of  plants,  such  as  the  Cruci- 
ferse,  which  contain  peculiar  sulphur  compounds  much  richer  in 
that  element  than  the  vegetable  constituents  of  blood.  The  seeds 
of  black  mustard,  the  horse-radish,  garlic,  onions,  and  scurvy- 
grass,  are  particularly  marked  in  this  respect.  From  all  of  these 
plants  we  obtain,  by  simple  distillation  with  water,  certain  vola- 
tile oils,  differing  from  all  other  organic  compounds  not  contain- 
ing sulphur,  by  their  peculiar,  pungent,  and  disagreeable  odor. 

Those  compounds  containing  sulphur  are  present  in  the  seeds 
of  all  plants,  as  well  as  in  the  plants  themselves  ;  and  as  they 
are  particularly  abundant  in  cultivated  plants  employed  for 
animal  nutrition,  it  is  quite  obvious  that  a  substance  containing 
sulphur  is  absolutely  essential  to  the  development  of  such  com- 
pounds, in  order  to  supply  to  them  their  proper  proportion  of  this 
element. 

It  is  also  obvious,  that  although  all  other  conditions  for  the 
nourishment  of  plants  be  present,  if  the  compound  containing 
sulphur  be  either  wholly  absent  or  deficient  in  quantity,  the  vege- 
table constituents  containing  sulphur  will  either  be  not  at  all 
formed,  or  they  will  be  generated  only  in  proportion  to  the  quan- 
tity of  the  above  compound.  The  air  cannot  contain  any  sub- 
stances in  which  sulphur  is  present,  unless  indeed  we  except 
minute  and  scarcely  appreciable  traces  of  sulphuretted  hydrogen. 
The  soil,  therefore,  must  be  the  only  means  of  furnishing  the 
sulphur  so  necessary  to  the  growth  of  plants ;  and  we  are 
ignorant  of  any  way  by  which  it  can  be  introduced  except 
through  the  roots. 

The  numerous  analyses  made  of  the  water  of  mineral  springs, 
furnish  us  with  a  satisfactory  explanation  of  the  form  in  which 
sulphur  occurs  in  soils.  The  water  of  such  springs  is  entirely 
derived  from  the  rain  which  falls  upon  the  surface  of  the  earth ; 
the  water  percolating  througl".   the  earth,   dissolves  all  soluble 


SUBSTANCES  YIELDING  SULPHUR.  «1 

materials  which  it  may  meet  in  its  course.  The  substances 
thus  dissolved  communicate  to  the  water  properties  which  are 
not  possessed  by  pure  water.  Water  procured  from  springs  or 
wells  is  found  to  be  very  rarely  deficient  in  soluble  salts  of  sul- 
phuric acid.  The  liquid  obtained  by  lixiviating  good  soil  from 
garden  or  arable  land  also  contains  very  appreciable  quantities 
of  these  salts. 

The  facts  now  detailed  leave  little  doubt  as  to  the  source 
whence  plants  obtain  their  sulphur.  As  far  as  our  knowledge 
extends,  they  receive  their  sulphur  from  the  sulphates  dissolved 
in  the  water  absorbed  by  their  roots  from  the  soil. 

Ammoniacal  salts,  particularly  sulphate  of  ammonia,  are 
rarely  detected  in  spring  water  ;  but  this  is  owing  to  the  con- 
stant presence  of  supercarbonate  of  lime,  Avhich  effects  their 
decomposition,  and  allows  the  escape  of  ammonia  during  the 
evaporation  of  the  liquid  for  the  purposes  of  analysis. 

According  to  our  view,  sulphate  of  ammonia  is  of  all  com- 
pounds containing  sulphur  the  one  most  fitted  for  the  assimilation 
of  that  element.  Sulphate  of  ammonia  contains  two  elements, 
both  of  which  are  equally  necessary  for  the  support  of  vegetable 
life ;  these  are  sulphur  and  nitrogen,  and  they  form  constituents 
also  of  vegetable  albumen,  fibrin,  and  casein.  But  what  is  still 
more  worthy  of  observation,  sulphate  of  ammonia,  viewing  it 
according  to  the  proportion  of  its  elements,  or  what  is  termed  its 
empirical  formula  (SO  ,,  N  H,,),  may  be  considered  as  a  com- 
pound of  water  with  equal  equivalents  of  sulphur  and  nitrogen. 
Thus,  by  the  simple  removal  of  the  elements  of  water  from  this 
compound,  its  sulphur  and  nitrogen  might  be  enabled  to  pass  over 
into  the  composition  of  the  plants. 

The  ingredients  of  plants  containing  sulphur  are  so  composed 
that  one  equivalent  of  sulphur  exists  for  every  25  equivalents 
of  nitrogen.  Hence  it  is  obvious  that  much  more  ammonia 
must  be  offered  to  plants  than  that  contained  in  the  form  of  sul- 
phate of  ammonia,  if  all  the  sulphur  of  the  latter  is  to  become  a 
constitueiit-of  the  organic  ingredients  alluded  to. 

This  bears  a  complete  analogy  to  the  assimilation  of  the  car- 
bon and  nitrogen  furnished  to  plants  in  the  form  of  carbonate  of 
ammonia.      This  salt  may  contain  two  equivalents  of  carbon  to 


ON  THE  SOURCE  OF  SULPHUR. 


one  equivalent  of  nitrogen.  Hence  it  is  necessary  that  the  car- 
bon of  six  equivalents  of  carbonic  acid  must  at  the  same  time  be 
taken  up,  and  enter  into  combination  with  the  nitrogen,  in  order 
to  produce  the  principal  nitrogenous  constituents  which  contain 
one  equivalent  of  nitrogen  to  eight  equivalents  of  carbon. 

The  passage  of  sulphur  derived  from  a  sulphate  into  the  com- 
position of  vegetable  matter,  necessarily  indicates  that  the  sul- 
phate has  been  exposed  to  the  action  of  the  same  causes  as  those 
by  which  the  decomposition  of  carbonic  acid  was  effected  in  the 
plant ;  and,  therefore,  that  the  sulphuric  acid  has  been  decom- 
posed into  sulphur  and  oxygen,  the  former  of  which  is  assimi- 
lated, whilst  the  latter  is  separated.  If  we  suppose  the  sulphuric 
acid  to  be  presented  in  the  form  of  sulphate  of  potash  or  soda,  the 
bases  of  these  salts  must  be  set  at  liberty  after  the  decomposition 
of  their  acid. 

Now  we  actually  find  these  bases  in  all  cultivated,  and  eveh 
in  most  wild  plants.  They  are  found  either  united  to  organic 
acids,  or,  what  is  still  more  remarkable,  they  are  found  in  union 
with  the  vegetable  compounds  containing  sulphur.  The  vege- 
table casein  of  peas,  beans,  and  other  leguminous  plants,  is  itself 
insoluble  in  water;  but  it  is  very  soluble  in  the  form  in  which 
it  occurs  in  the  plant.  This  solubility  is  due  to  the  soda  and 
potash  with  which  it  is  united.  In  like  manner,  the  albumen 
contained  in  the  juices  of  plants  is  combined  with  an  alkali ;  and 
we  must  suppose  that  vegetable  fibrin,  the  insoluble  ingredient  of 
cereal  plants,  must  have  originally  been  soluble,  and  have  at- 
tained its  position  in  the  seeds  by  the  agency  of  alkalies. 

The  potash  and  soda  of  the  alkaline  sulphates  which  furnish  to 
plants  their  sulphur,  remain,  therefore,  either  in  combination 
with  the  ingredients  containing  that  element,  or  they  enter  into 
some  new  state  of  combination,  or,  finally,  they  are  returned  to 
the  soil. 

Gypsum  (sulphate  of  lime)  is  the  most  generally  diffused  sul- 
phate. Being  soluble,  it  may  either  pass  directly  into  the  plant, 
or  ii  may  be  decomposed  by  the  carbonate  of  ammonia  existing 
in  rain-water,  when  its  sulphur  will  pass  into  the  plant  in  the 
form  of  sulphate  of  ammonia. 

A   solution  of  gypsum  containing  common  salt  or  chloride 


MIXTURE  OF  GYPSUM  AND  OF  SALT.  6% 

of  potassium,  such  as  sea-water,  and  the  water  of  most  springs, 
may  be  viewed  as  a  mixture  of  an  alkaline  sulphate  with 
chloride  of  calcium.  From  this  it  must  be  obvious,  that  when 
we  furnish  to  a  plant  at  the  same  time  both  gypsum  and  common 
salt  (chloride  of  sodium),  we  actually  furnish  by  such  a  solution 
the  same  materials  that  we  would  do  if  we  supplied  a  mixture 
of  sulphate  of  soda  and  chloride  of  calcium.  In  order  to  form 
the  constituents  containing  sulphur,  that  element  and  the  alkali 
must  be  retained  by  the  plant,  while  the  chlorine  and  calcium 
will  be  expelled  by  the  roots* 

We  know  that  this  process  actually  does  take  place  in  the 
case  of  marine  plants.  The  soda  or  potash  is  obtained  from 
common  salt  or  chloride  of  potassium,  which  suffers  decomposi- 
tion  by  the  presence  of  sulphate  of  lime  or  sulphate  of  magnesia. 
It  is  necessary  to  suppose  that  this  process  also  occurs  with  the 
cereal  and  all  other  plants,  the  ashes  of  which  are  destitute  of 
lime,  and  the  sulphur  of  which  has  been  supplied  in  the  form  of 
gypsum.  Thus  we  are  enabled  to  explain  the  use  of  common 
salt  as  a  manure  ;  it  enables  the  plant,  for  which  this  manure  is 
useful,  to  extract  its  sulphur  from  the  soil  in  which  it  existed  in 
the  form  of  sulphate  of  lime. 


64         OF  THE  INORGANIC  CONSTITUENTS  OF  PLANTS. 


CHAPTER    VII. 

Of  the  Inorganic  Constituents  of  Plants.* 

Carbonic  acid,  water,  ammonia,  and  sulphates,  are  necessary 
for  the  existence  of  plants,  because  they  contain  the  elements 
from  which  their  organs  are  formed  ;  but  other  substances  are 
likewise  requisite  for  the  formation  of  certain  organs  destined 
for  special  functions  peculiar  to  each  family  of  plants.  Plants 
obtain  these  substances,  as  they  do  the  sulphur  they  contain, 
from  inorganic  nature.  In  the  ashes  left  after  the  incineration 
of  plants,  the  same  substances  are  found,  although  in  a  changed 
condition. 

Many  of  the  inorganic  constituents  vary  according  to  the  soil 
in  which  the  plants  grow,  but  a  certain  number  of  them  are  in- 
dispensable to  their  development.  All  substances  in  solution  in 
a  soil  are  absorbed  by  the  roots  of  plants,  exactly  as  a  sponge 
imbibes  a  liquid,  and  all  that  it  contains,  without  selection.  The 
substances  thus  conveyed  to  plants  are  retained  in  greater  or 
less  quantity,  or  are  entirely  separated  when  not  suited  for 
assimilation. 

Alkaline  and  earthy  phosphates  form  invariable  constituents 
of  the  seeds  of  all  kinds  of  grasses,  of  beans,  peas,  and  lentils. 

These  salts  are  introduced  into  bread  along  with  the  flour,  and 

*  "  Many  authors,"  says  Saussure,  "  consider  that  the  mineral  ingredi- 
ents of  plants  are  merely  accidentally  present,  and  are  not  at  all  necessary 
to  their  existence,  because  the  quantity  of  such  substances  is  exceedingly 
small.  This  opinion  may  be  true  as  far  as  regards  those  matters  which 
are  not  always  found  in  plants  of  the  same  kind  ;  but  there  is  certainly  no 
evidence  of  its  truth  with  those  invariably  present.  Their  small  quantity 
does  not  indicate  their  inutility.  The  phosphate  of  lime  existing  in  the 
animal  body  does  not  amount  to  the  fifth  part  of  its  weight,  yet  no  one 
doubts  that  this  salt  is  necessary  for  the  formation  of  its  bones.  I  have 
detected  the  same  compound  in  the  ashes  of  all  plants  submitted  to  exami- 
nation, and  we  have  no  right  to  suppose  that  they  could  exist  without  it,** 
(Be  SaussurCy  p.  241.) 


IMPORTANCE  OF  ALKALINE  BASES.  65 

into  beer  along  with  barley.  The  bran  of  flour  contains  a  large 
quantity  of  ammoniacal  phosphate  of  magnesia.  This  salt  forms 
large  crystalline  concretions,  often  amounting  to  several  pounds 
in  weight,  in  the  ccecum  of  horses  belonging  to  millers  ;  and 
when  ammonia  is  mixed  with  beer,  the  same  salt  separates  as  a 
white  precipitate. 

Most  plants,  perhaps  all  of  them,  contain  organic  acids  of  very 
different  composition  and  properties,  all  of  which  are  in  combina- 
tion  with  bases,  such  as  potash,  soda,  lime,  or  magnesia ;  plants 
containing  free  organic  acids  are  few  in  number.  These  bases 
evidently  regulate  the  formation  of  the  acids,  for  the  diminution 
of  the  one  is  followed  by  a  decrease  of  the  other :  thus  in  the 
grape,  for  example,  the  quantity  of  acid  contained  in  its  juice  is 
less  when  it  is  ripe  than  when  unripe  ;  and  the  bases,  under  the 
same  circumstances,  are  found  to  vary  in  a  similar  manner. 
Such  constituents  exist  in  the  smallest  quantity  in  those  parts  of 
a  plant  in  which  the  process  of  assimilation  is  most  active,  as  in 
the  mass  of  woody  fibre  ;  and  their  quantity  is  greatest  in  those 
organs  whose  office  it  is  to  prepare  substances  conveyed  to  them 
for  assimilation  by  other  parts.  The  leaves  contain  more  inor- 
ganic matters  than  the  branches,  and  the  branches  more  than  the 
stem  (Sauss[jre).  The  potatoe  plant  contains  more  potash  before 
blossoming  than  after  it  (Mollerat). 

The  acids  found  in  the  different  families  of  plants  are  of  vari- 
ous kinds ;  it  cannot  be  supposed  that  their  presence  and  peculi- 
arities are  the  result  of  accident.  The  fumaric  and  oxalic  acids 
in  the  lichens,  the  kinic  acid  in  the  RubiacecB,  the  rocellic  acid 
in  the  Rocella  tinctoria,  the  tartaric  acid  in  grapes,  and  the  nu- 
merous other  organic  acids,  must  serve  some  end  in  vegetable 
life.  But  if  these  acids  constantly  exist  in  vegetables,  and  are 
necessary  to  their  life,  which  is  incontestable,  it  is  equally  cer- 
tain that  sonrie  alkaline  base  is  also  indispensable,  in  order  to  enter 
into  combination  with  the  acids  ;  for  these  are  always  found  in 
the  state  of  neutral  or  acid  salts.  All  plants  yield  by  incineration 
ashes  containing  carbonic  acid  ;  all,  therefore,  must  contain  salts 
of  an  organic  acid.* 

*  Salts  of  organic  acids  yield  carbonates  on  incineration,  if  they  contaiu 
cither  alkaline  or  earthy  bases. 


«6  OF  THE  INORGANIC  CONSTITUENTS  OF  PLANTS. 


Now,  as  we  know  the  capacity  of  saturation  of  organic  acids 
to  be  unchanging,  it  follows  that  the  c  uantity  of  the  bases  united 
with  them  cannot  vary  ;  and  for  this  reason  the  latter  substances 
ought  to  be  considered  with  the  strictest  attention,  both  by  the 
agriculturist  and  physiologist. 

We  have  no  reason  to  believe  that  a  plant  in  a  condition  of 
free  and  unimpeded  growth  produces  more  of  its  peculiar  acids 
than  it  requires  for  its  own  existence  ;  hence,  a  plant,  on  what- 
ever soil  it  grows,  must  contain  an  invariable  quantity  of  alkaline 
bases.     Culture  alone  will  be  able  to  cause  a  deviation. 

In  order  to  understand  this  subject  clearly,  it  will  be  necessary 
to  bear  in  mind  that  any  one  of  many  of  the  alkaline  bases  may 
be  substituted  for  another,  the  action  of  all  being  the  same.  Our 
conclusion  is,  therefore,  by  no  means  endangered  by  the  exist- 
ence in  one  plant  of  a  particular  alkali  which  may  be  absent  in 
others  of  the  same  species.  If  this  inference  be  correct,  the 
absent  alkali  or  earth  must  be  supplied  by  one  similar  in  its  mode 
of  action,  or  in  other  words,  by  an  equivalent  of  another  base. 
The  number  of  equivalents  of  these  various  bases  which  may  be 
combined  with  the  acid  in  a  given  plant  must  consequently  be  a 
constant  quantity,  and  therefore  the  amount  of  oxygen  contained 
in  them  must  remain  unchanged  under  all  circumstances  and  on 
whatever  soil  they  grow.* 

*  When  sulphuric  acid  is  placed  in  contact  with  potash,  soda,  lime,  or 
magnesia,  the  properties  both  of  the  acid  and  of  the  alkali  disappear,  and 
if  the  proportions  have  been  just,  the  compound  thus  produced  is  a  neutral 
sulphate  of  these  bases. 

100  parts  of  sulphuric  acid  require  for  neutralization  very  different  quanti- 
ties of  the  above  bases;  thus,  to  effect  this  purpose,  it  is  necessary  to  em- 
ploy 118  parts  of  potash,  7S  parts  of  soda,  71  "2  parts  of  lime,  and  51  "6  parts 
of  magnesia. 

In  order  to  produce  a  neutral  nitrate  with  118  parts  of  potash  (the  quan- 
tity necessary  to  saturate  100  parts  of  sulphuric  acid),  we  must  employ  135 
parts  of  nitric  acid.  Now,  when  we  examine  how  much  soda,  lime,  or 
magnesia  is  required  to  saturate  the  same  quantity  of  nitric  acid  (135  parts) 
it  is  found  that  complete  saturation  is  effected  by  7S  of  soda,  7r2  of  lime, 
51  "6  of  magnesia,  or  exactly  the  same  quantities  as  in  the  case  of  sulphuric 
acid.  It  is  quite  indifferent  what  acids  we  use  to  neutralize  their  bases,  or 
how  much  the  numbers  obtained  may  differ  from  those  now  stated ;  still 
the   relative  proportion  remains  invariable.     If  for  the  saturation  of  anjf 


INVARIABLE  QUANTITY  OF  ALKALINE  BASES.  6' 


Of  course,  this  argument  refers  only  to  those  alkaline  bases 
which  in  the  form  of  organic  salts  form  constituents  of  the  plants. 
Now,  these  salts  are  preserved  in  the  ashes  of  plants  as  carbon- 
ates, the  quantity  of  which  can  be  easily  ascertained.  The 
bases  contained  in  the  bark  do  not  any  longer  belong  to  the  vital 
organism  of  the  plant. 

It  has  been  distinctly  shown,  by  the  analyses  of  De  Saussure 
and  Berthicr,  that  the  nature  of  a  soil  exercises  a  decided  influ- 
ence on  the  quantity  of  the  different  metallic  oxides  contained  in 
the  plants  which  grow  on  it;  that  magnesia,  for  example,  was 
contained   in  the   ashes  of  a  pine-tree  grown  at   Mont  Breven, 

particular  acid  51  "6  parts  of  magnesia  have  been  used,  we  may  be  perfectly 
certain  that  the  same  quantity  of  this  acid  will  be  exactly  neutralized  by 
78  parts  of  soda. 

We  have  now  to  state  the  causes  which  occasion  this  unequal  power  of 
these  metallic  oxides  to  neutralize  acids  We  have  also  to  expLiin  why,  to 
produce  the  same  efiect,  it  is  necessary  to  employ  a  smaller  quantity  of  soda, 
and  only  one  half  the  quantity  of  magnesia  that  we  would  use  of  potash, 
and  still  that  the  relative  quantities  are  constant  with  all  acids, 

A  knowledge  of  the  composition  of  the  bases  has  afforded  us  a  very  sijn 
pie  explanation  of  these   causes.     All   the  bases  now  mentioned  contain 
oxygen  combined  with  a  metal ;   and  their  capacity  of  saturation  depends 
upon  the  quantity  of  oxygen  contained  within  them. 

Although  the  absolute  quantities  of  the  above  bases  are  so  very  different, 
they  all  contain  the  same  quantities  of  oxygen. 

Oxygen  contained. 
100  Sulphuric  Acid  neutralize  118  Potash      =  20 
100         "  "  "  78  Soda  =  20 

100         "  "  "  71-2  Lime         =  20 

100         "  "  "  51-6  Magnesia  =  20 

Now,  if  we  neutralize  100  parts  of  sulphuric  acid  with  potash  and  soda, 
or  with  potash,  soda,  and  lime,  or  with  potash,  soda,  lime,  and  magnesia, 
the  sulphuric  acid  unites  with  quantities  of  two,  three,  or  four  bases  exactly 
corresponding  to  their  united  quantity  of  oxygen.  This  may  be  represent- 
ed in  the  following  table  : — 

100  parts  sulphuric  acid  neutralize      <  Sodium"        \  '^^  P'^rts  oxygen. 

C  Potassium  ^ 

100     "  "  "         "  <  Sodium  V  20     "     oxygen. 

f  Calcium  ) 

(Potassium  ^ 


iM; 


gnesium 


flS         OF  THE  INORGANIC  CONSTITUENTS  OF  PLANTS 

whilst  it  was  absent  from  the  ashes  of  a  tree  of  the  same  species 
from  Mont  La  Salle,  and  that  the  proportion  of  lime  and  potash 
was  also  very  different. 

Hence  it  has  been  concluded  (erroneously,  I  believe),  that  the 
presence  of  bases  exercises  no  particular  influence  upon  the 
growth  of  plants :  but  even  were  this  view  correct,  it  must  be 
considered  as  a  most  remarkable  accident  that  these  same  analyses 
furnish  proof  for  the  very  opposite  opinion.  For  although  the 
composition  of  the  ashes  of  these  pine-trees  was  so  very  different, 
they  contained,  according  to  the  analyses  of  De  Saussure,  an 
equal  number  of  equivalents  of  metallic  oxides ;  or,  what  is  the 
same  thing,  the  quantity  of  oxygen  contained  in  all  the  bases  was 
m  both  cases  the  same. 

100  parts  of  the  ashes  of  the  pine-tree  from  Mont  Breven  con- 
tained— 

Carbonate  of  Potash     .    3*60      Quantity  of  oxygen  in  the  Potash     .  0*415 

Lime       .  4G-34  "  '"         "        Lime        .  7-327 

"  Magnesia     677  "  "         "        Magnesia.  1-2G5 

Sum  of  the  carbonates     50  71         Sum  of  the  oxygen  in  the  bases        9"007 

100  parts  of  the  ashes  of  the  pine  from  Mont  La  Salle  con- 
tained— * 

Carbonate  of  Potash     .    7*36      Quantity  of  oxygen  in  the  Potash     .    0-85 
Lime       .  51-19  "  "         "        Lime        .    8-10 

"  Magnesia  00  00 

Sum  of  the  carbonates    5S5.3         Sum  of  the  oxygen  in  the  bases  8-0-"> 

The  numbers  9-007  and  8-95  approach  each  other  ns  nearly 
as  could  be  expected  even  in  analyses  made  for  the  very  purpose 
of  ascertaining  the  fact  above  demonstrated  ;  which  the  analyst 
in  this  case  ha<l  not  in  view. 

Let  us  now  compare  Berthier's  analyses  of  the  ashes  of  two 
fir-trees,  one  of  which  grew  in  Norway,  the  other  in  Allevard 
{departement  de  risdre).     One  contained  50,  the  other  25  per 

*  According  to  the  experiments  of  Saussure,  1000  parts  of  the  wood  of 
the  pine  from  Mont  Breven  gave  11-87  parts  of  ashes;  the  same  quantity 
of  wood  froiK  Mont  La  Salle  yielded  11-28  parts. 


INVARIABLE  QUANTITY  OF  ALKALINE  BASES.  89 

cent  of  soluble  salts.  A  greater  difference  in  the  proportion  of 
the  alkaline  bases  could  scarcely  exist  between  two  totally  dif- 
ferent plants,  and  yet  even  here  the  quantity  of  oxygen  in  the 
bases  of  both  was  the  same. 

loo  parts  of  the  ashes  of  firwood  from  Allevard  contained, 
according  to  Berthier  (Ann.  de  Chim.  et  de  Phys.,  t.  xxxii., 
p.  248), 

Potash  and  Soda  16*8  in  which  3 "57  parts  must  be  oxygen 
Lime         .         .     29'6         "  8-36  "  " 

Magnesia  .       3-3        *«  1-26  "  •* 

49-7  13-19 

Only  part  of  the  potash  and  soda  in  these  ashes  was  in  com- 
bination with  organic  acids  ;  the  remainder  was  in  the  form  of 
sulphates,  phosphates,  and  chlorides.  One  hundred  parts  of 
the  ashes  contain  0*797  sulphuric  acid,  3*12  phosphoric  acid, 
and  0*077  hydrochloric  acid,  which  together  neutralize  a  quan- 
tity of  base  containing  0*53  oxygen.  This  number,  therefore, 
must  be  subtracted  from  13*19.  The  remainder,  12*66,  indi- 
cates the  quantity  of  oxygen  in  the  alkaline  bases,  combined 
with  organic  acids  in  the  firwood  of  Allevard. 

The  firwood  of  Norway  contained  in  100  parts, — 

Potash    .  .  14*1   of  which  24    parts  would  be  oxygen. 

Soda        .  .  20-7         "           5-3 

Lime      .  .  13G         "          382 

Magnesia  .       4*35       "          I'GO 

52-75  13-21 

And  if  we  subtract  from  13*21  the  quantity  of  oxygen  of  the 
bases  in  combination  with  sulphuric  and  phosphoric  acid,  viz., 
0*79,  12*42  parts  remain  as  the  amount  of  oxygen  contained  in 
the  bases  which  were  in  combination  with  organic  acids. 

These  remarkable  approximations  cannot  be  accidental ;  and 
if  future  investigations  confirm  them  in  other  kinds  of  plants,  no 
other  explanation  than  that  already  given  can  be  adopted. 

It  is  not  known  in  what  form  manganese,  and  oxide  of  iron, 
are  contained  in  plants ;  but  we  are  certain  that  potash,  soda, 


70         OF  THE  INORGANIC  CONSTITUENTS  OF  PLANTS. 

and  magnesia,  can  be  extracted  by  means  of  water  from  all  parts 
of  their  structure  in  the  form  of  salts  of  organic  acids.  The 
same  is  the  case  with  lime,  when  not  present  as  insoluble  oxalate 
of  lime.  It  must  here  be  remembered,  that  in  plants  yielding 
oxalic  acid,  tlie  acid  and  potash  never  exist  in  the  form  of  the 
neutral  oxalate  or  quadroxalate,  but  always  as  a  binoxalate,  on 
whatever  soil  they  may  grow.  The  potash  in  grapes  is  always 
found  as  an  acid  salt,  viz.,  cream  of  tartar  (bitartrate  of  potash), 
and  never  in  the  form  of  a  neutral  compound.  As  these  acidg 
and  bases  are  never  absent  from  plants,  and  as  even  the  form  in 
which  they  present  themselves  is  not  subject  to  change,  it  may 
be  affirmed  that  they  exercise  an  important  influence  on  the 
development  of  tho  fruits  and  seeds,  and  also  on  many  other 
functions,  of  tlie  nature  of  which  we  are  at  present  ignorant. 
The  quantity  of  alkaline  bases  existing  in  a  plant  also  depefids 
evidently  on  this  circumstance  of  their  existing  only  in  the  form 
of  salts  of  certain  acids, — for  the  capacity  of  saturation  of  an  acid 
is  constant. 

From  these  considerations  we  must  perceive,  that  exact  and 
trustworthy  examinations  of  the  ashes  of  plants  of  the  same 
kind  growing  upon  different  soils  would  be  of  the  greatest  im- 
portance to  vegetable  physiology,  and  would  decide  whether  the 
facts  above  mentioned  are  the  results  of  an  unchanging  law  for 
each  family  of  plants,  and  whether  an  invariable  number  can  be 
found  to  express  the  quantity  of  oxygen  which  each  species  of 
plant  contains  in  the  bases  united  with  organic  acids.  In  all  pro- 
bability such  inquiries  will  lead  to  most  important  results ;  for  it 
is  clear  that  if  the  production  of  a  certain  unchanging  quantity 
of  an  organic  acid  is  required  by  the  peculiar  nature  of  the 
organs  of  a  plant,  and  is  necessary  to  its  existence,  then  potash 
or  lime  must  be  taken  up  by  it  in  order  to  form  salts  with  this 
acid  ;  that  if  these  do  not  exist  in  sufficient  quantity  in  the  soil, 
other  alkaline  bases,  of  equal  value,  must  supply  their  place  ; 
and  that  the  progress  of  a  plant  must  be  wholly  arrested  when 
none  are  present. 

Seeds  of  the  Salsola  kali,  when  sown  in  common  garden  soil, 
produce  a  plant  containing  both  potash  and  soda ;  while  the  planta 


SUBSTITUTION  OF  ALKALINE  BASES.  71 

grown  from  the  seeds  of  this  contain  only  salts  of  potash,  with 
mere  traces  of  muriate  of  soda.*     (Cadet.) 

The  existence  of  vegetable  alkalies  in  combination  with  organic 
acids  gives  great  weight  to  the  opinion  that  alkaline  bases  in 
general  are  connected  with  the  development  of  plants. 

If  potatoes  are  grown  where  they  are  not  supplied  with  earth, 
the  magazine  of  inorganic  bases  (in  cellars,  for  example),  a  true 
alkali,  called  Solanin,  of  very  poisonous  nature,  is  formed  in  the 
sprouts  extending  towards  the  light,  while  mere  traces  of  such  a 
substance  can  be  discovered  in  the  roots,  herbs,  blossoms,  or  fruits 
of  potatoes  grown  in  fields  (Otto).  In  all  the  species  of  the 
Cinchona,  Idnic  acid  is  found ;  but  the  quantity  of  quinina,  cin- 
chonina,  and  lime  contained  in  them  is  most  variable.  From  the 
fixed  bases  in  the  products  of  incineration,  however,  we  may  esti- 
mate pretty  accurately  the  quantity  of  the  peculiar  organic  bases. 
A  maximum  of  the  first  corresponds  to  a  minimum  of  the  latter, 
as  must  necessarily  be  the  case  if  they  mutually  replace  one 
another  according  to  their  equivalents.  We  know  that  different 
kinds  of  opium  contain  meconic  acid  in  combination  with  very 
different  quantities  of  narcotina,  morphia,  codeia,  &c.,  the  quan- 
tity of  one  of  these  alkaloids  diminishing  on  the  increase  of  the 
others.  Thus  the  smallest  quantity  of  morphia  is  accompanied 
by  a  maximum  of  narcotina.  Not  a  trace  of  meconic  acidf  can 
be  discovered  in  many  kinds  of  opium,  but  there  is  not  on  this 

*  "  We  planted,"  says  Wiegmann  and  Polstorf,  "  several  plants  in  a 
flower-pot  filled  with  common  earth  iVom  the  garden,  and  watered  them 
with  a  weak  solution  of  chloride  of  potassium,  having  previously  ascer- 
tained that  the  earth  contained  mere  traces  of  metallic  chlorides.  Sub- 
jected to  this  treatment,  the  plants  flourished  very  luxuriantly,  so  much 
so  that  they  completely  covered  the  flower-pot,  stretching  far  over  its 
sides.  We  now  transplanted  them  into  the  open  soil,  and  did  not  supply 
them  any  longer  with  chloride  of  potassium  ;  but,  in  the  following  year, 
they  shrunk  and  died  during  the  period  of  blossoming.  It  follows,  from 
the  experiments  which  we  have  detailed,  that  both  kinds  of  plants  re- 
quired metallic  chlorides  for  their  proper  nourishment,  but  that  it  is  quiU 
indifferent  whether  the  chlorine  be  united  with  sodium  or  potassium." 
{Preischrift  iiber  die  anorganischen  Bestandtheile  der  Pflanzen.) 

t  Robiquet  did  not  obtain  a  trace  of  meconate  of  lime  from  309  lb? 
of  opium,  whilst  in  other  kinds  the  quantity  was  very  considerabU 
{Ann.  de  Chim  ,  liii. ,  p  425) 


72  OF  THE  INORGANIC  CONSTITUENTS  OF  PLANTS. 

account  an  absence  of  acid,  for  the  meconic  is  here  replaced  by 
sulphuric  acid.  Here,  also,  we  have  an  example  of  what  has 
been  before  stated  ;  for  in  those  kinds  of  opium  where  both  these 
acids  exist,  they  are  always  found  to  bear  a  certain  relative  pro- 
portion to  one  another. 

Now  if  it  be  found,  as  appears  to  be  the  case  in  the  juice  of 
poppies,  that  an  organic  acid  may  be  replaced  by  an  inorganic 
without  impeding  the  growth  of  a  plant,  we  must  admit  the  pro- 
bability of  this  substitution  taking  place  in  a  much  higher  degree 
in  the  case  of  the  inorganic  bases. 

When  roots  find  their  more  appropriate  base  in  sufficient 
quantity,  they  will  take  up  less  of  another. 

These  phenomena  will  not  show  themselves  so  frequently  in 
cultivated  plants,  because  they  are  subjected  to  special  external 
conditions,  for  the  purpose  of  the  production  of  particular  con- 
stituents or  of  particular  organs. 

By  sprinkling  with  the  juice  of  the  Phytolacca  dexandra,  the 
soil  in  which  a  white  hyacintli  is  growing  in  a  state  of  blossom, 
its  white  blossoms  assume  in  one  or  two  hours  a  red  color,  which 
again  disappears  after  a  few  days  under  the  influence  of  sunshine, 
and  they  become  white  and  colorless  as  before.*  The  juice  in 
this  case  evidently  enters  into  all  parts  of  the  plant,  without 
being  at  all  changed  in  its  chemical  nature,  or  without  its 
presence  being  apparently  either  necessary  or  injurious.  But 
this  condition  is  not  permanent,  and  when  the  blossoms  have 
again  become  colorless,  none  of  the  coloring  matter  remains  ; 
and  if  it  should  occur  that  any  of  its  elements  were  adapted  for 
the  purposes  of  nutrition  of  the  plant,  then  these  alone  would  be 
retained,  whilst  the  rest  would  be  excreted  in  an  altered  form  by 
the  roots. 

Exactly  the  same  thing  must  happen  when  we  sprinkle  a  plant 
with  a  solution  of  chloride  of  potassium,  nitre,  or  nitrate  of 
strontia  ;  they  will  enter  into  the  difl^erent  parts  of  the  plant,  just 
as  the  colored  juice  mentioned  above,  and  will  be  found  in  its 
ashes  if  it  should  be  burnt  at  this  period.     Their  presence  is 


•  Biot,  in  the  Comptes  rendus  des  Stances  de  I'Acad^mie  dea  Scieiico^ 
ft  Paris,  premier  Sfemestre,  1837,  p.  12. 


EXCREMExNTS  OF  PLANTS.  73 

merely  accidental ;  but  this  does  not  furnish  ground  for  any  con- 
clusion against  the  necessity  of  the  presence  of  other  bases  in 
plants.  The  experiments  of  Macaire-Princep  Jiave  shown,  that 
plants  made  to  vegetate  with  their  roots  in  a  weak  solution  of 
acetate  of  lead,  and  then  in  rain-water,  yield  to  the  latter  all  the 
salt  of  lead  which  they  had  previously  absorbed.  They  return, 
therefore,  to  the  soil  all  matters  unnecessary  to  their  existence. 
Again,  when  a  plant,  freely  exposed  to  the  atmosphere,  rain  and 
sunshine,  is  sprinkled  with  a  solution  of  nitrate  of  strontia,  the 
salt  is  absorbed,  but  it  is  again  separated  by  the  roots  and 
removed  further  from  them  by  every  shower  of  rain  that  falls 
upon  the  soil,  so  that  at  last  not  a  trace  of  it  is  to  be  found  in  the 
plant.  (Daubeny.)  Let  us  consider  the  composition  of  the 
ashes  of  the  two  fir-trees  above  mentioned  as  analysed  by  an 
acute  and  most  accurate  chemist.  One  of  these  grew  in  Nor- 
way, on  a  soil  of  invariable  composition,  but  to  which  soluble 
salts,  and  particularly  common  salt,  were  conveyed  in  great 
quantity  l)y  rain-water.  How  did  it  happen  that  its  ashes  con- 
tained no  appreciable  trace  of  salt,  although  we  are  certain  that 
lis  roots  must  have  absorbed  it  after  every  shower  ? 

We  can  explain  the  absence  of  salt  in  this  case  by  means 
of  the  direct  and  positive  observations  referred  to,  which  have 
shown  that  plants  have  the  power  of  returning  to  the  soil  all 
substances  unnecessary  to  their  existence  ;  and  the  conclusion  to 
which  all  the  foregoing  facts  lead  us,  when  their  real  value  and 
bearing  are  apprehended,  is  that  the  alkaline  bases  existing  in 
the  ashes  of  plants  must  be  necessary  to  their  growth,  since  if 
this  were  not  the  case  they  would  not  be  retained. 

The  perfect  development  of  a  plant,  according  to  this  view,  is 
dependent  on  the  presence  of  alkalies  or  of  alkaline  earths ;  for 
when  these  substances  are  totally  wanting  its  growth  will  be  ar- 
rested, and  when  they  are  only  deficient  it  must  be  impeded. 

In  order  to  apply  these  remarks,  let  us  compare  two  kinds  of 
trees,  the  wood  of  which  contains  unequal  quantities  of  alkaline 
bases,  and  we  shall  find  that  one  of  these  may  grow  luxuriantly 
in  several  soils  upon  which  the  other  is  scarcely  able  to  vegetate.  « 
For  example,  10,000  parts  of  oak-wood  yield  250  parts  of  ashes, 


74  OF  THE  INORGANIC  CONSTITUENTS  OF  PLANTS. 

the  same  quantity  of  fir-wood  only  83,  of  lime-wood  500,  of  rye 
440,  and  of  the  herb  of  the  potatoe  plant  1500  parts.* 

Firs  and  pines  find  a  sufficient  quantity  of  alkalies  in  granitic 
and  barren  sandy  soils  in  which  oaks  will  not  grow  ;  and  wheat 
thrives  in  soils  favorable  for  the  lime-tree,  because  the  bases 
necessary  to  bring  it  to  complete  maturity  exist  there  in  suffi- 
cient quantity.  The  accuracy  of  these  conclusions,  so  highly 
important  to  agriculture  and  to  the  cultivation  of  forests,  can  be 
proved  by  the  most  evident  facts. 

All  kinds  of  grasses,  and  the  Equisetacc(2,  for  example,  con- 
tain in  the  outer  parts  of  their  leaves  and  stalk,  a  large  quantity 
of  silicic  acid  and  potash  in  the  form  of  acid  silicate  of  potash.  The 
proportion  of  this  salt  does  not  vary  perceptibly  in  the  soil  of 
corn-fields,  if  it  be  again  conveyed  to  them  as  manure  in  the  form 
of  putrefying  straw.  But  this  is  not  the  case  in  a  meadow,  and 
hence  we  never  find  a  luxuriant  crop  of  grass  f  on  sandy  and  cal- 
careous soils  containing  little  potash,  evidently  because  one  of  the 
cor.stituents  indispensable  to  the  growth  of  the  plants  is  wanting. 
Soils  formed  from  basalt,  grauwacke,  and  porphyry,  are,  ccBteris 
paribus,  the  best  for  meadow-land,  on  account  of  the  large  quan- 
tity of  potash  they  contain.  The  potash  abstracted  by  the 
plants  is  restored  during  the  annual  irrigation.  The  amount  of 
alkalies  contained  in  the  soil  itself  is  very  great  in  com- 
parison with  the  quantity  removed  by  plants,  although  not 
inexhaustible. 

A  harvest  of  grain  is  obtained  every  thirty  or  forty  years 
from  the  soil  of  the  Luneburg  heath  by  strewing  it  with  the 
ashes  of  the  heath-plants  {Erica  vulgaris)  growing  upon  it. 
These  plants,  during  the  long  period  just  mentioned,  collect  the 
potash  and  soda  contained  in  the  soil  and  conveyed  to  them  by 
rain-water  ;  and  it  is  by  means  of  these  alkalies  that  oats,  barley, 
and  rye,  to  which  they  are  indispensable,  are  enabled  to  grow  on 
this  sandy  heath. 

*  Berthier,  Annales  de  Chimie  et  de  Physique,  t.  xxx.,  p,  248. 

f  It  would  be  of  importance  to  examine  what  alkalies  are  contained  in 

the  ashes  of  the  sea-shore  plants  which  grow  in  the  humid  hollows  of 

*down8,  and  especially  those  of  the  millet-grass      If  potash  is  not  found  io 

them,  it  must  certainly  be  replaced  by  soda,  as  in  the  Salsota,  or  by  lime, 

M  in  the  Plttmbaginea. 


REPIACEMENT  OF  EXHAUSTED  ALKALIES.  "S 

The  woodcutters  in  the  vicinity  of  Heidelberg  have  the  privi- 
lege of  cultivating  the  soil  for  their  own  use,  after  felling  the 
trees  used  for  making  tan.  Before  sowing  the  land  thus  obtained, 
the  branches,  roots,  and  leaves,  are  in  every  case  burned,  and 
the  ashes  used  as  a  manure,  which  is  found  to  be  quite  indispen- 
sable for  the  growth  of  the  grain.  The  soil  itself  upon  which 
the  oaks  grow  in  this  district  consists  of  sandstone  ;  and  although 
the  trees  find  in  it  a  quantity  of  alkaline  earths  sufficient  for 
their  own  sustenance,  yet  in  its  ordinary  condition  it  is  incapable 
of  producing  cereal  crops. 

The  most  decisive  proof  of  the  use  of  strong  manure  was  ob- 
tained at  Bingen  (a  town  on  the  Rhine),  where  the  produce  and 
development  of  vines  were  highly  increased  by  manuring  them 
with  such  nitrogenous  manures  as  shavings  of  horn,  &c.  ;  but 
after  some  years  the  formation  of  the  wood  and  leaves  decreased 
to  the  great  loss  of  the  proprietor,  to  such  a  degree  that  he  has 
long  had  cause  to  regret  his  departure  from  the  usual  methods, 
ascertained  by  long  experience  to  be  the  best.  By  the  manure 
employed  by  him,  the  vines  had  been  too  much  hastened  in  their 
growth ;  in  two  or  three  years  they  had  exhausted  the  potash  in 
the  formation  of  their  fruit,  leaves,  and  wood,  so  that  none  re- 
mained for  the  future  crops,  his  manure  not  having  contained 
any  potash. 

There  are  vineyards  on  the  Rhine,  the  plants  of  which  are 
above  a  hundred  years  old,  and  all  of  these  have  been  cultivated 
by  manuring  them  with  cow-dung,  a  manure  containing  a  large 
proportion  of  alkaline  ingredients,  although  very  little  nitrogen. 
All  the  alkalies,  in  fact,  contained  in  the  food  consumed  by  a 
cow  are  again  immediately  discharged  in  the  liquid  excrements. 

The  leaves  and  small  branches  of  trees  contain  the  greatest 
quantity  of  ashes  and  of  alkalies  ;  and  the  quantity  of  them  annu- 
ally removed  from  a  wood,  for  the  purpose  of  being  employed  as 
litter,*  contain  much  more  of  the  alkalies  than  all  the  old  wood 

*  [This  refers  to  a  custom  some  time  since  very  prevalent  in  Germany, 
although  now  discontinued.  The  leaves  and  small  twigs  of  trees  were 
gleaned  from  the  forests  by  poor  people,  for  the  purpose  of  being  used  af 
litter  for  their  cattle.  The  trees,  however,  were  found  to  suffer  so  much 
in  consequence,  that  their  removal  is  now  strictly  prohibited.  The  cause 
of  the  injury  was  that  stated  in  the  text. — Ed.] 


76  OF  THE  INORGANIC  CONSTITUENTS  OF  PLANTS. 

cut  down.  The  bark  and  foliage  of  oaks,  for  example,  contain 
from  6  to  9  per  cent,  of  alkalies,  the  needles  of  firs  and  pines,  8 
per  ceLt. 

With  every  2650  lbs.  of  firwood  yearly  removed  from  an  acre 
of  forest,  only  7  or  8  lbs.  of  alkalies  are  abstracted  from  the  soil, 
calculating  the  ashes  at  0.83  per  cent.  The  leaves,  however, 
cover  the  soil,  and  being  very  rich  in  alkalies,  in  comparison 
with  the  wood,  retain  those  alkalies  on  the  surface,  which  would 
otherwise  so  easily  penetrate  with  the  rain  through  the  sandy 
soil.  By  their  decay  an  abundant  provision  of  alkalies  is  sup- 
plied to  the  roots  of  the  trees,  and  a  fresh  supply  is  rendered 
unnecessary. 

The  ashes  of  the  tobacco  plant,  of  the  vine,  of  peas,  and  of 
clover,  contain  a  large  quantity  of  lime.  Such  plants  do  not 
flourish  on  soils  devoid  of  lime.  By  the  addition  of  salts  of  lime 
lo  such  soils,  they  become  fitted  for  the  growth  of  these  plants  ; 
for  we  have  every  reason  to  believe  that  their  development  es- 
sentially depends  upon  the  presence  of  lime.  Tiie  presence  of 
magnesia  is  equally  essential,  there  being  many  plants,  such  as 
the  different  varieties  of  beet  and  potatoes,  from  which  it  is  never 
absent. 

The  supposition  that  alkalies,  metallic  oxides,  or  inorganic  mat- 
ter in  general,  are  produced  by  plants,  is  entirely  refuted  by 
these  well-authenticated  facts. 

It  is  thought  very  remarkable,  that  the  plants  of  the  grass 
tribe,  fitted  for  the  food  of  man,  follow  him  like  the  domestic 
animals.  But  saline  plants  seek  the  sea-shore  or  saline  springs, 
and  the  Chenopodium  the  dunghill,  from  similar  causes.  Saline 
plants  require  common  salt,  and  the  plants  growing  only  on  dung- 
hills need  ammonia  and  nitrates,  and  they  are  attracted  to  places 
where  these  can  be  found,  just  as  the  dung-fly  is  to  animal  ex- 
crements. So  likewise  none  of  our  corn  plants  can  bear  perfect 
seeds,  that  is,  seeds  yielding  flour,  without  a  large  supply  of 
phosphate  of  magnesia  and  ammonia,  substances  which  they  re- 
quire for  their  maturity.  And  hence,  these  plants  grow  only  in 
a  soil  where  these  three  constituents  are  found  combined,  and  no 
soil  is  richer  in  them  than  those  where  men  and  animals  dwell 
together ;  where  the  urine  and  excrements  of  these  are  found 


NECESSITY  OF  CERTAIN  COiNDITIONS  FOR  NUTRITION.     77 

com  plants  appear,  because  their  seeds  cannot  attain  maturity 
unless  supplied  with  the  constituents  of  those  matters. 

When  we  find  sea  plants  near  our  salt-works,  several  hundred 
miles  distant  from  the  sea,  we  know  that  their  seeds  have  been 
carried  there  in  a  very  natural  manner,  namely,  by  wind  or  by 
birds,  which  have  spread  them  over  the  whole  surface  of  the 
earth,  although  they  grow  only  in  those  places  in  which  they  find 
the  conditions  essential  to  their  life. 

Numerous  small  fish,  of  not  more  than  two  inches  in  length 
(Gasterosteus  aculeatus),  are  found  in  the  salt-pans  of  the  gradu- 
ating-house  at  Nidda  (a  village  in  Hesse  Darmstadt).  No  living 
animal  is  found  in  the  salt-pans  of  Neuheim,  situated  about  18 
miles  from  Nidda  ;  but  the  water  there  contains  so  much  car- 
bonic acid  and  lime,  that  the  walls  of  the  graduating-house  are 
covered  with  stalactites.  Hence  the  eggs  conveyed  to  this  place, 
by  whatever  cause,  do  not  find  the  conditions  necessary  for  their 
development,  although  they  did  so  in  the  former  place. 

How  much  more  wonderful  and  inexplicable  does  it  appear, 
that  bodies,  remaining  fixed  in  the  strong  heat  of  a  fire,  have  un- 
der certain  conditions  the  property  of  volatilizing  and,  at  ordinary 
temperatures,  of  passing  into  a  state,  of  which  we  cannot  say 
whether  they  have  really  assumed  the  form  of  a  gas  or  are  dis- 
solved in  one  !  Steam  or  vapors  in  general  have  a  very  singu- 
lar influence  in  causing  the  volatilization  of  such  bodies,  that  is 
of  causing  them  to  assume  the  gaseous  form.  A  liquid  during 
evaporation  communicates  the  power  of  assuming  the  same  state 
in  a  greater  or  less  degree  to  all  substances  dissolved  in  it, 
although  they  do  not  of  themselves  possess  that  property. 

Boracic  acid  is  a  perfectly  fixed  substance ;  it  suffers  no 
change  of  weight  appreciable  by  the  most  delicate  balance,  when 
exposed  to  a  white  heat,  and  therefore  it  is  not  volatile.  Yet  its 
solution  in  water  cannot  be  evaporated  by  the  gentlest  heat,  with- 
out the  escape  of  a  sensible  quantity  of  the  acid  with  the  steam. 
Hence  it  is  that  a  loss  is  always  experienced  in  the  analysis  of 
minerals  containing  this  acid,  when  liquids  in  which  it  is  dissolved 
are  evaporated.  The  quantity  of  boracic  acid  which  escapes 
with  a  cubic  foot  of  steam,  at  the  temperature  of  boiling  water, 
cannot  be  detected  by  our  most  sensible  re-agents;  but  neverthe. 


78  OF  THE  INORGANIC  CONSTITUENTS  OF  PLANTS. 

less  the  many  hundred  tons  annually  brought  from  Italy  as  an 
article  of  commerce,  are  procured  by  the  uninterrupted  accu- 
mulation of  this  apparently  inappreciable  quantity.  The  hot 
steam  issuing  from  the  interior  of  the  earth,  passes  through  cold 
water  in  the  lagoons  of  Castel  Nuovo  and  Cherchiago ;  in  this 
way  the  boracic  acid  is  gradually  accumulated,  till  at  last  it  may 
be  obtained  in  crystals  by  the  evaporation  of  the  water.  It  is 
evident,  from  the  temperature  of  the  steam,  that  it  must  have 
come  out  of  depths  in  which  human  beings  and  animals  never 
could  have  lived,  and  yet  it  is  very  remarkable  and  highly 
important  that  ammonia  is  never  absent  from  it.  In  the  large 
works  in  Liverpool,  where  natural  boracic  acid  is  converted  into 
borax,  many  hundred  pounds  of  sulphate  of  ammonia  are  obtained 
at  the  same  time. 

This  ammonia  has  not  been  produced  by  the  animai  or> 
ganism,  but  existed  before  the  creation  of  human  beings, 
being  a  part,  a  primary  constituent,  of  the  globe  itself. 

The  experiments  instituted  under  Lavoisier's  guidance  by  the 
Direction  des  Poudrcs  et  SalpHres,  have  proved  that  during  the 
evaporation  of  the  saltpetre  ley,  the  salt  volatilizes  with  the  water, 
and  causes  a  loss  which  could  not  before  be  explained.  It  is 
known  also  that,  in  sea-storms,  leaves  of  plants  in  the  direction 
of  the  wind  are  covered  with  crystals  of  salt,  even  at  the  dis- 
tance of  from  20  to  30  miles  from  the  sea.  But  it  does  not 
require  a  storm  to  cause  the  volatilization  of  the  salt,  for  the  air 
hanging  over  the  sea  always  contains  enough  of  this  substance 
to  render  turbid  a  solution  of  nitrate  of  silver,  and  every  breeze 
must  carry  this  away.  Now,  as  thousands  of  tons  of  sea-water 
annually  evaporate  into  the  atmosphere,  a  corresponding  quantity 
of  the  salts  dissolved  in  it,  viz.,  of  common  salt,  chloride  of  potas- 
sium, magnesia,  and  the  remaining  constituents  of  the  sea-water, 
will  be  conveyed  by  wind  to  the  land. 

This  volatilization  is  a  source  of  considerable  loss  in  salt- 
works, especially  where  the  proportion  of  salt  in  the  water  is 
small.  This  has  been  completely  proved  at  the  salt-works  of 
Nauheim,  by  the  very  intelligent  director  of  that  establishment, 
M.  Wilhelmi.  He  hung  a  plate  of  glass  between  two  evaporat- 
ing houses,  distant  about  1200  paces  from  each  other,  and  found 


INORGANIC  ORIGIN  OF  AMMONIA. 


.n  the  morning,  after  the  drying  of  the  dew,  that  the  glass  was 
covered  with  crystals  of  salt  on  one  or  the  other  side,  according 
to  the  direction  of  the  wind. 

By  the  continual  evaporation  of  the  sea,  its  salts*  are  spread 
over  the  whole  surface  of  the  earth  ;  and  being  subsequently 
carried  down  by  the  rain,  furnish  to  vegetation  those  salts  nece*. 
sary  to  its  existence.  This  is  the  origin  of  the  salts  found  in  the 
ashes  of  plants,  in  those  cases  where  the  soil  could  not  have 
yielded  them. 

In  a  comprehensive  view  of  the  phenomena  of  nature,  we  have 
no  scale  for  that  which  we  are  accustomed  to  name  small  or 
great ;  all  our  ideas  are  proportioned  to  what  we  see  around  us ; 
but  how  insignificant  are  they  in  comparison  with  the  whole 
mass  of  the  globe  !  that  which  is  scarcely  observable  in  a  con- 
fined district  appears  inconceivably  large  when  regarded  in  its 
extension  through  unlimited  space.  The  atmosphere  contains 
only  a  thousandth  part  of  its  weight  of  carbonic  acid  ;  and  yet 
small  as  tliis  proportion  appears,  it  is  quite  sufficient  to  supply 
the  whole  of  the  present  generation  of  living  beings  with  car- 
bon for  thousands  of  years,  even  if  it  were  not  renewed.  Sea- 
water  contains  i^^Iqq  of  its  weight  of  carbonate  of  lime  ;  and 
t'lis  quantity,  although  scarcely  appreciable  in  a  pound,  is  the 

*  According  to  Marcet,  sea- water  contains  in  1000  parts, 
26-660  Chloride  of  Sodium. 
4-660  Sulphate  of  Soda. 
1"232  Chloride  of  Potassium. 
5-152  Chloride  of  Magnesium. 
1*5      Sulphate  of  Lime. 


39-201 
According  to  Clemm,  the  water  of  the  North  Sea  contains  in  1000  parts, 
24-84  Chloride  of  Sodium. 
2'42  Chloride  of  Magnesium. 
2-06  Sulphate  of  Magnesia. 
1-31  Chloride  of  Potassium 
1-20  Sulphate  of  Lime. 
In  addition  to  these  constituents,  it  also  contains  inappreciable  quanti- 
ties of  carbonate  of  lime,  magnesia,  iron,  manganese,  phosphate  of  iime, 
iodides,  and  bromides,  and  organic  matter,  together  with  ammonia  and 
carbonic  acid. — Liebig's  Annalen  der  Cherme.  Bd.  xxxvii.,  s.  3. 


M  OF  THE  INORGANIC  CONSTITUENTS  OF  PLANTS. 


source  from  which  myriads  of  marine  mollusca  and  corals  are 
supplied  with  materials  for  their  habitations. 

Whilst  the  air  contains  only  from  4  to  6  ten-thousandth  parti 
of  its  volume  of  carbonic  acid,  sea-water  contains  100  times 
more  (10,000  volumes  of  sea-water  contain  620  volumes  of  car- 
bonic acid — Laurent,  Bouillon-Lagrange).  Ammonia*  is  also 
found  in  this  water  ;  so  that  the  same  conditions  which  sustain 
living  beings  on  the  land  are  combined  in  this  medium,  in  which 
a  whole  world  of  other  plants  and  animals  exist. 

The  roots  of  plants  are  constantly  engaged  in  collecting  from 
the  rain  those  alkalies  which  formed  part  of  the  sea-water,  and 
also  those  of  the  water  of  the  springs  penetrating  the  soil.  With- 
out alkalies  and  alkaline  bases  most  plants  could  not  exist,  and 
without  plants  the  alkalies  would  disappear  gradually  from  the 
surface  of  the  earih. 

When  it  is  considered  that  sea- water  contains  less  ihan  one- 
millionth  of  its  own  weight  of  iodine,  and  that  all  combinations 
of  iodine  with  the  metallic  bases  of  alkalies  are  highly  soluble 
in  water,  some  provision  must  necessarily  be  supposed  to  exist 
in  the  organization  of  sea- weed  and  the  different  kinds  of  Fuci, 
by  which  they  are  enabled  during  their  life  to  extract  iodine  in 
the  form  of  a  soluble  salt  from  sea-water,  and  to  assimilate  it  in 
such  a  manner,  that  it  is  not  again  restored  to  tlie  surrounding 
medium.  These  plants  are  collectors  of  iodine,  just  as  land 
plants  are  of  alkalies  ;  and  they  yield  us  this  element  in  quanti- 
ties such  as  we  could  not  otherwise  obtain  from  the  water  without 
the  evaporation  of  whole  seas. 

We  take  it  for  granted,  that  the  sea  plants  require  metallic 
iodides  for  their  growth,  and  that  their  existence  is  dependent  on 
the  presence  of  those  substances.  With  equal  justice,  then,  we 
conclude,  that  the  alkalies  and  alkaline  earths  always  found  in 
the  ashes  of  land  plants,  are  likewise  necessary  for  their  deve- 
lopment. 

*  When  the  solid  saline  residue  obtained  by  the  evaporation  of  sea 
water  is  lieated  in  a  retort  to  redness,  a  sublimate  of  sal-ammoniac  \f 
obtained. — Marcet. 


DISINTEGRATION  OF  ROCKS. 


CHAPTER  VIII. 

On  the  Formation  of  Arable  Land. 

The  hardest  rocks  and  stones  gradually  lose  their  coherence 
when  exposed  to  the  influence  of  certain  agencies.  Soils  con- 
sist of  the  debris  of  rocks  which  have  suffered  this  change. 

The  disintegration  of  minerals  and  rocks  is  effected  partly  by 
mechanical,  and  partly  by  chemical  means.  It  has  been  re- 
marked in  all  the  mountainous  districts  of  perpetual  snow,  that 
the  most  refractory  rocks  crumble  into  fragments,*  which  are 
either  rounded  by  the  action  of  glaciers,  or  are  thoroughly  pul- 
verized into  dust.  The  rivers  and  streams  arising  out  of  the 
glaciers  are  rendered  turbid  with  this  mineral  debris  which  they 
deposit  on  reaching  the  plains  and  valleys  ;  thus  fertile  soils  are 
formed. 

"  As  often  as  I  have  seen  beds  of  mud,  sand,  and  shingle, 
accumulated  to  the  thickness  of  many  thousand  feet,  I  have  felt 
inclined  to  exclaim,  that  causes  such  as  the  present  rivers  and 
the  present  beaches  could  never  have  ground  down  such  masses. 
But,  on  the  other  hand,  when  listening  to  the  rattling  noise  of 
these  torrents,  and  calling  to  mind  that  whole  races  of  animals 
have  passed  away  from  the  surface  of  the  globe,  during  the 
period  throughout  which,  night  and  day,  these  stones  have  gone 
rattling  onwards  in  their  course,  I  have  thought  to  myself.  Can 
any  mountains,  any  continent,  withstand  such  waste  ?"  f 

*  "  I  frequently  observed,  both  in  Terra  del  Fuego  and  within  the 
Andes,  that  where  the  rock  was  covered  during  the  greater  part  of  the 
year  with  snow,  it  was  shivered  in  a  very  extraordinary  manner  into  small 
angular  fragments.  Scoresby  has  observed  the  same  fact  in  Spitzhergen  ; 
he  says  :  '  The  invariably  broken  state  of  the  rocks  appeared  to  have  been 
the  effects  of  frost.'  " — Darwin's  JVat.  Hist,  of  the  Voyage  of  the  Beagle, 
p.  388. 

t  Darwin,  Nat.  Hist,  of  the  Voyage  of  the  Beagle,  p.  386 
5* 


FORMATION  OF  SOILS. 


In  addition  to  these  mechanical  causes  of  waste,  we  have  to 
consider  tlie  influence  exerted  by  chemical  forces  in  eflfecting  the 
disintegration  of  rocks,  such  as  the  action  of  the  oxygen  and 
carbonic  acid  of  the  air,  as  well  as  that  of  water,  upon  their 
constituent  parts.  Whilst  we  apply  the  term  waste  to  the 
effects  produced  by  mechanical  agencies,  we  shall  confine  the 
term  disintegration  to  the  effects  produced  by  chemical  forces. 
The  latter  causes  may  be  very  gradual  in  their  operation,  not 
being  limited  in  regard  to  time.  Hence  we  cannot  refuse  to 
acknowledge  the  existence  of  their  action,  even  though  the  effect 
produced  may  not  be  sensible  during  the  life  of  an  individual. 

Many  years  are  necessary  before  the  polished  surface  of  an 
exposed  fragment  of  granite  loses  its  polish  ;  but  in  process 
of  time  this  is  effected,  and  the  large  fragment  falls  to  pieces 
under  the  influence  exerted  upon  its  constituents  by  the  chemi- 
cal forces. 

The  action  of  water  is  so  much  connected  with  that  of  oxygen 
and  of  carbonic  acid,  that  it  is  scarcely  possible  to  consider  their 
effects  apart. 

Many  kinds  of  rocks,  such  as  basalt  and  clay-slate,  contain  as 
an  ingredient  protoxide  of  iron.  This  oxide  has  a  great  tendency 
to  absorb  oxygen  from  the  air,  becoming  the  higher  oxide  known 
as  peroxide  of  iron.  This  property  is  especially  apparent  in  our 
rich  ferruginous  soils.  The  surface  of  such  soils  to  a  certain 
depth  is  of  a  red  or  brownish-red  color,  an  indication  that  it  con- 
tains peroxide  of  iron  ;  whilst  the  black  or  brownish-black  color 
of  the  subsoil  indicates  the  presence  of  tlie  protoxide  of  the  same 
metal.  It  often  happens  that  the  subsoil  is  thrown  upon  the  sur- 
face in  the  course  of  subsoil-ploughing,  and  the  consequence  on 
such  soils  is,  that  their  fertility  is  destroyed  for  a  certain  number 
of  years.  The  injury  thus  received  continues  until  all  the  sur- 
face-soil again  becomes  red,  that  is,  until  all  the  protoxide  of 
iron  is  converted  into  the  peroxide. 

It  is  known  that  a  crystallized  salt  of  iron  loses  its  coherence 
on  exposure  to  air,  and  crumbles  into  a  powder  by  the  absorption 
of  oxygen.  In  a  similar  manner  the  disintegration  of  most 
minerals  is  effected,  for  their  ingredients  are  susceptible  of  en- 
tering into  union  with  oxygen.     In  consequence  of  the  formation 


PROPERTIES  OF  SILICA. 


of  new  compounds,  the  coherence  of  the  original  body  is 
destroyed.  If  the  minerals  contain  metallic  sulphurets,  such 
as  the  pyrites  in  granite,  these  are  gradually  converted  into 
sulphates. 

Most  kinds  of  rocks,  such  as  felspar,  basalt,  clay-slate,  por- 
phyry, and  the  numerous  members  of  the  limestone  formation, 
consist  of  compounds  of  silica,  with  alumina,  lime,  potash,  soda, 
iron,  and  protoxide  of  manganese. 

Before  we  can  properly  comprehend  the  action  of  water  and 
of  carbonic  acid  upon  minerals,  it  is  necessary  to  recollect  the 
properties  of  silica  and  of  its  compounds  with  alkaline  bases. 

Quartz  forms  a  very  pure  variety  of  silica,  and,  in  this  condi- 
tion, it  is  quite  insoluble  both  in  cold  and  in  hot  water,  is  with- 
out taste,  and  does  not  exert  any  action  on  vegetable  colors. 
The  principal  property  of  silica  in  this  state  is,  that  it  unites  with 
alkalies,  forming  saline  compounds,  which  are  termed  silicates. 
Window  and  plate  glass  consist  of  mixtures  of  silicates  of  the 
alkaline  bases,  potash,  soda,  and  lime.  In  such  compounds  the 
alkali  is  generally  completely  neutralized.  The  property  of 
neutralizing  metallic  oxides  and  alkalies  belongs  only  to  acids, 
and  it  is  owing  to  this  that  silica  has  received  the  name  of  silicic 
acid. 

Silica  is  a  very  feeble  acid,  for  we  have  already  mentioned 
that,  in  its  crystallized  form,  it  is  destitute  both  of  taste  and  of 
solubility  in  water  ;  but  t  dissolves  when  finely  pulverized  and 
lK)iled  for  a  long  time  in  alkaline  leys. 

We  may  easily  obtain  compounds  of  silica  with  potash  and 
soda,  by  melting  it  either  with  a  pure  alkali,  or  with  an  alkaline 
carbonate.  By  this  treatment  white  glasses  are  obtained,  differ- 
ing in  properties  according  to  their  amount  of  soluble  ingre- 
dients. When  llie  glass  contains  70  per  cent,  of  silica  and  30 
per  cent,  of  potash  or  soda,  it  becomes  soluble  in  boiling  water. 
Its  solution  may  be  spread  over  a  surface  of  wood  or  of  iron,  and 
then  dries  into  a  vitreous  substance,  which  has  received  the 
name  of  soluble  glass.  When  there  is  a  smaller  proportion  of 
alkali  than  the  above  quantity,  or,  in  other  words,  when  there  is 
a  larger  proportion  of  silica,  the  resulting  glass  diminishes  4|| 
solubility  in  a  greater  or  less  degree.  ,.  ..-v 


B^  I'ORMATION  OF  SOILS. 


All  silicates  soluble  in  water  are  decomposed  by  acids.  If  the 
solution  of  the  silicate  contains  silica  corresponding  to  more 
than  -^Q-  the  weight  of  the  water,  the  addition  of  an  acid  causes 
the  formation  of  a  precipitate  of  a  very  gelatinous  appearance. 
This  precipitate,  being  a  compound  of  silica  with  water,  is 
termed  the  hydrate  of  silica.  But,  if  the  solution  contains  less 
silica  than  the  above  proportion,  no  precipitate  is  formed  on  the 
addition  of  an  acid,  the  whole  remaining  perfectly  clear.  This 
circumstance  proves  that  silica,  in  the  state  in  which  it  is  preci- 
pitated by  an  acid,  possesses  a  certain  degree  of  solubility  in 
pure  water.  Indeed,  by  washing  with  water  the  gelatinous  pre- 
cipitate of  silica  formerly  alluded  to,  its  volume  diminishes,  and 
silica  may  be  detected  in  solutio:^  by  evaporating  the  wate» 
which  has  passed  through. 

From  these  facts  we  perceive,  that  silica  possesses  two  distirt  • 
chemical  characters.  In  the  form  in  which  it  is  separated  fiorr* 
a  silicate,  it  possesses  quite  different  properties  from  those  whic^ 
it  has  when  in  the  state  of  sand,  quartz,  or  rock  crystal.  Whei* 
sufficient  water  is  present  during  its  separation  from  a  base,  U 
effect  its  solution,  the  whole  remains  dissolved  ;  in  certaip 
conditions,  silica  is  more  soluble  in  water  than  gypsum. 

On  drying,  silica  loses  completely  its  solubility  in  watrs 
The  solution  of  silica  in  acids  acquires,  at  a  certain  degree  o? 
concentration  after  cooling,  such  a  gelatinous  consistence  tha'* 
the  vessel  containing  it  may  be  turned  upside  down  withoiM 
spilling  a  drop  of  the  transparent  jelly.  By  drying  it  stiR 
further,  the  water  which  retained  it  in  the  gelatinous  condition 
escapes  along  with  that  which  had  served  to  hold  it  in  solutior . 
When  the  water  has  been  onco  removed  in  this  way,  the  silici^ 
is  no  longer  soluble  in  water.  But,  although  it  has  thus  lost  its 
solubility,  it  does  not  acquire  all  the  properties  of  crystallizedi 
silica,  such  as  sand  and  quartz,  for  it  still  possesses  the  power  o* 
dissolving  in  alkalies  and  alkaline  carbonates  at  the  ordinary 
temperature  of  the  air,  and  this  power  it  retains  even  when  i* 
has  been  heated  to  redness. 

There  is  scarcely  any  other  mineral  substance  which  can  b* 
compared  to  silica  for  the  possession  of  such  remarkable  proper 
ties  as  those  now  described. 


DECOMPOSITION  OF  FELSPAR.  85 

Most  of  the  insoluble  silicates  containing  alkaline  bases  are 
decomposed  by  the  action  of  hot  water,  particularly  when  that 
water  contains  an  acid.  In  the  middle  of  the  last  century,  the 
ignorance  of  this  fact  led  chemists  to  believe  that  \Vater  might 
be  converted  into  an  earth. 

When  water  is  distilled  in  glass  vessels,  it  is  found  to  contain 
always  a  certain  quantity  of  earthy  substances,  which  may  be 
detected  by  evaporation,  even  if  the  water  has  been  subjected  to 
many  repeated  distillations.  Lavoisier  proved  that  part  of  the 
glass  was  dissolved  in  this  operation  by  the  boiling  water ;  and 
further,  that  the  diminution  in  the  weight  of  the  glass  vessel  cor- 
responded exactly  to  the  quantity  of  earthy  residue  left  by  the 
evaporation  of  the  water.  When  the  distillation  of  water  is 
effected  in  metallic  vessels  no  such  residue  can  be  obtained. 

The  action  of  water  upon  the  silicates  contained  in  glass  may 
be  observed  in  the  opacity  which  gradually  comes  over  the  win- 
dows of  hot-beds,  these  being  exposed  in  a  great  degree  to  the 
influence  of  the  air.  This  action  is  more  marked  in  the  win 
dows  of  stables,  where  the  carbonic  acid  formed  by  the  processes 
of  respiration  of  the  animals,  and  by  the  decay  of  animal  matter, 
accelerates  the  decomposition. 

Silica  being  an  acid  of  a  very  feeble  character,  the  decompo- 
sition of  the  soluble  silicates  is  effected  even  by  carbonic  acid. 

A  solution  of  soluble  glass  may  be  converted  into  a  gelatinous 
mass  by  saturating  it  with  carbonic  acid  gas.  The  same  decom- 
position must  take  place  in  very  dilute  sotutions,  although  we 
cannot  detect  in  them  any  separation  of  silica,  which  remains 
dissolved  in  the  water. 

The  decomposition  of  silicates  by  the  combined  action  of  water 
and  of  acids  proceeds  with  a  rapidity  proportional  to  the  quantity 
of  alkalies  contained  in  them. 

We  find  numerous  examples  in  the  inorganic  kingdom  of  a  con- 
tinued and  progressing  process  of  decomposition  of  the  silicates 
contained  in  the  various  kinds  of  rocks  ;  this  decomposition  is  ef- 
fected by  the  action  of  carbonic  acid,  and  of  water. 

A  consideration  of  the  preceding  observations  shows  clearly 
that  porcelain  clay  or  kaolin  has  been  formed  by  the  decompos- 
ing action  of  water  on  the  silicates  of  potash  and  soda  contained 


FORMATION  OF  SOILS. 


in  felspar  or  felspathic  rocks.  Felspar*  may  be  viewed  as  m 
combination  of  silicate  of  alumina  with  silicate  of  potash ;  the 
last  of  which  being  gradually  removed  by  water,  leaves  behind 
the  porcelain  clay. 

It  has  been  shown  by  Forchammer,  that  felspar  may  be  de- 
composed by  water  of  150°  C.  (302°  F.),  and  at  a  pressure  cor- 
responding to  this  temperature.  The  water  becomes  strongly 
alkaline,  and  is  found  to  contain  silica  in  solution.  The  hot 
springs  in  Iceland  possess  a  high  temperature,  and  come  from  a 
great  depth,  where  they  must  have  been  subjected  to  high  pres- 
sure. Forchammer  has  shown  by  analysis  that  the  water  of 
these  springs  contains  the  constituents  of  soda  felspars,  and  of 
magnesian  silicates,  minerals  of  very  frequent  occurrence  in 
trap  districts.  There  cannot  be  a  doubt  that  a  conversion  of 
crystalline  felspar  into  clay  must  be  proceeding  to  a  great  extent 
at  the  bottom  of  these  springs. f 

Ordinary  water  containing  carbonic  acid  acts  in  precisely 
the  same  manner  as  water  at  a  high  temperature,  and  at  a  high 
pressure. 

Polstorf  and  Wiegmann  boiled  some  white  sand  with  a  mixture 
of  nitric  and  muriatic  acids,  and  after  completely  removing  the 

*  COMPOSITION    OF   FELSPATHIC  MINERALS. 

Felspar.  Albit.  Labrador.  A  north. 

Silica  -  -  -  56-9  -  -  69-8  -  -  558  -  -  44'5 
Alumina  -  -  -  178  -  -  18-8  -  -  26-5  -  -  34-5 
Potash  -  -  -  16-3  -  -  —  -  _  _  .  -  — 
Soda  -  -  -  _  .  .  11-4  -  -  4-0  -  -  — 
Magnesia  -  -  -  —  -  -  —  -  -  —  -  -8'2 
Lime  -  -  -  —  -  .  _  .  .  iro  -  -  15-7 
Protoxide  of  iron       -      —      -         -      —      -         -1'3-         -0'7 

The  chemical  formula  of  felspar  is  AI2,  O3   3  Si  0,   +  KO,  Si  0».o 
f  his  formula,  when  multiplied  by  three,  may  be  divided  into  porcelain 
clay,  3  Ala,  O3,  4  Si  O3,  and  into  soluble    silicate  of  potash,  3 Ko,  8 
SiO». 
t  The  dry  residue  of  28  ounces  of  the  water  consisted  of— 
Gypsum        -        -         -         -      0453 
Sulphate  of  Soda  >  a.qo'i 

Magnesia  5         "         -0  827 

Common  Salt        -        -        -      2  264 

Soda 1-767 

Silica  .        .        -        •        .      0-506 


ANALYSIS  OF  PHONOLITE.  -W 

acid  by  washing  the  sand  with  water,  they  exposed  it  thus  puri- 
fied to  the  action  of  water  saturated  with  carbonic  acid  gas. 
After  the  expiration  of  thirty  days,  this  water  was  subjected  to 
analysis,  and  was  found  to  contain  in  solution,  silica,  carbonate 
of  potash,  and  also  lime  and  magnesia  ;  thus  proving  that  the 
silicates  contained  in  the  sand  were  unable  to  withstand  the  con- 
tinued action  of  water  containing  carbonic  acid,  although  the 
same  silicates  had  resisted  the  short  action  of  the  aqua  regia. 

Certain  of  the  alkaline  silicates  found  in  nature  contain  in  their 
crystalline  state  water  in  chemical  combination.  In  this  class 
are  the  zoolites,  analcime,  mesotypc,  sodalite,  apophyllite,  <^g.  ; 
the  felspars,  properly  so  called,  arc  always  anhydrous. 

These  silicates  differ  very  much  in  their  behavior  to  acid 
reagents.  When  mesotype,  or  a  mineral  correspond  in  jj  to  it  in  com- 
position, is  kept  in  the  state  of  a  fine  powder  in  contact  with  cold 
muriatic  acid,  it  increases  in  bulk  to  a  thick  jelly.  The  mineral 
being  exposed  to  the  action  of  the  acid  at  the  ordinary  tempera- 
ture,  those  constituents  which  are  soluble  in  the  acid  are  taken 
up  by  it,  whilst  the  greatest  part  of  the  silica  remains  undissolv- 
ed. Labrador  spar  (calcareous  felspar)  behaves  similarly  when 
treated  with  acids  ;  but  the  minerals  adularia  and  albite  (potash 
and  soda  felspars)  are  not  attacked  by  acids  under  similar  cir- 
cumstances. 

The  difference  in  properties,  with  respect  to  reagents,  enables 
us  to  decompose  very  complex  kinds  of  rocks  into  their  constitu- 
ent parts.  C.  Gmelin  used  a  process  in  the  analysis  of  phonolite, 
or  clinkstone  rock,  by  which  we  may  separate  and  determine 
the  amount  of  the  minerals  capable  of  disintegration  contained 
in  different  kinds  of  rocks  or  soils  submitted  to  examination.  For 
example,  phonolite  from  Abtcrode  in  the  district  of  Hegau  wa« 
found  to  contain* — 

2*097  of  a  mineral  analogous  to  mesotype,  and  soluble  in  acid* 
11 '142  of  felspar,  insoluble  in  acids 

The  constituents  of  both  these  are  as  follows : — 
•  Poggendorf *s  Annalen,  Bd.  x.,p  357, 


FORMATION  OF  SOILS. 


The  portion  Insc'.ub'.e 

soluble  in  acids.  residue. 

Silica       -        -         .         -     38  574    -  -    66-291 

Alumina-        -         -         -     24-320     -  -     16-510 

Potash      -         -         -         -       3079     -  -       9-249 

Soda         -         -         -         .     12-656     -  -       4-960 

Lime        -         -         -         .       i  802     -  -   A  trace. 

Peroxide  of  iron       -         -     11*346     -  -      2-388 

Peroxide  of  manganese     -      2-194     -  -       0-896 
Titanic  acid     -         -         -       0620 
Water     ...        -      4209 
Organic  substances  -         -       0  4  05 
Jn  a  similar  manner,  Frick  has  analysed  clay  slate,  and  Lowe 
the  basalt  and  lava  from  Mount  Etna. 

C   4-615  Magnetic  Iron  Ore. 
Basalt  contains  in  100  parts      <  39  800  Zeolite.* 
(  55-885  Augite.f 

By  treating  clay  slate  from  Bendorf  with  muriatic  acid,  it  was 
decomposed  into — 

26-4G  parts  soluble  in  muriatic  acid. 
73-54  parts  insoluble  in  muriatic  acid. 

The  composition  of  these  was  as  follows  :■ — 

Soluble  part  Insoluble  part 

of  clay  slate.  of  clay  slato. 

Silica 22-39  -  -         -     7706 

Alumina 19-35  -  -         -     1599 

Peroxide  of  iron 27-61  -  -         -       1-53 

Magnesia 7-00  -  .         .       0  57 

Lime 242  -  -         -       3-94 

Potash  without  soda        .        -        -         .       237  -  -         -      3*94 

Water,  carbonic  acid,  and  loss         -        -     18-86  -  -         -      0-39 
Oxide  of  copper     -----            -_-_      0-19 

From  these  analyses  we  may  deduce  some  highly  important 
reiults. 

It  is  known  that  felspar  is  unable  to  resist  the  solvent  action 

*  Zeolite  contains — 

Silica  .        -        .         -        -  38-83 

Alumina 28*77 

Lime 1045 

Soda 13-81 

Potash 1-42 

Water 672 

t  Augite  is  a  silicate  of  lime  and  magnesia 


FORMATION  OF  CLAYS. 


89 


of  water,  saturated  with  carbonic  acid,  although  it  is  scarcely 
affected  by  being  left  in  contact  with  cold  muriatic  acid  for 
twenty-four  hours.  The  analyses  given  above  show  that  the 
most  widely  diffused  rocks  contain  a  mixture  of  silicates,  which, 
being  soluble  in  cold  muriatic  acid,  must  be  much  more  easily 
attacked  than  felspar  by  water  holding  in  solution  carbonic  acid. 

All  minerals  and  rocks  containing  silicates  of  alkaline  bases 
are  incapable  of  resisting  the  continued  solvent  action  of  carbonic 
acid  dissolved  in  water.  The  alkalies,  with  lime  and  magnesia, 
will  either  dissolve  alone,  or  the  former  will  enter  into  solution 
along  with  silica,  while  the  alumina  remains  behind,  mixed  or 
combined  with  silica.  Disintegrated  phonolite  from  Abterode, 
formed  by  the  action  of  air  and  moisture  on  the  solid  mineral 
(the  analysis  of  which  is  given  above),  behaves  to  acids  in  a 
manner  quite  different  from  the  latter. 

The  mineral  clinkstone  contains  more  than  20  per  cent,  of 
ingredients  soluble  in  muriatic  acid,  whilst  the  same  mineral, 
when  disintegrated,  does  not  contain  more  than  5  per  cent,  of 
soluble  constituents.* 

The  insoluble  portion  of  disintegrated  phonolite  is  scarcely 
altered. in  composition:  in  the  soluble  portion,  iron  and  mangan- 
ese form  the  principal  constituents  :  these  two  oxides  exist  in  the 
soluble  portions  of  the  undisintegrated  mineral  in  the  proportion 
of  11-346  :  2-194  ;  and  in  the  disintegrated  mineral,  100  parts 
contain  63-39  of  peroxide  of  iron  to  11-3  of  peroxide  of  man- 
ganese, or  nearly  the  same  proportion  as  the  former. 

In  the  process  of  disintegration,  therefore,  the  alkalies,  lime, 
and  magnesia,  have  been  dissolved  and  carried  away  by  water 
along  with  silica  and  alumina  ;  and  the  residue  contains  only  -^ 
the  amount  of  the  alkalies  originally  present.  But  as  long  as 
the  mineral  contains  a  trace  of  an  alkali,  or  of  any  base  soluble 


•  The  soluble  part  of  disintegrated 

The  insoluble  portion  of  disinte- 

clinkstone contains — 

grated  clinkstone  contains— 

Silica     -         -         -         - 

13-396 

Silica     - 

-         -         - 

66-462 

Alumina         -         -         _ 

5-660 

Alumina 

-         -         - 

16810 

Potash  (Soda) 

1-07.1 

Potash 

-         -         - 

9-569 

Lime      .        -        -        . 

Soda      - 

> 

4-281 

Peroxide  of  Iron     - 

63-396 

Lime      - 

,         -         - 

1-523 

Peroxide  of  Manganese  - 

11  132 

Peroxide  of  Iron    - 

2-989 

Titanic  Acid 

3-396 

Peroxide  of 

Manganese 

0-173 

FORMATION  OF  SOILS. 


in  carbonic  acid,  water  containing  that  gas  continues  to  exercise 
an  action  upon  it,  and  effects  a  progressive  disintegration  of  its 
constituents. 

Forchammor  considers  that  the  yellow  clay,  which  occurs  so 
frequently  in  Denmark,  consists  of  granite,  the  felspar  of  which 
has  been  altered,  whilst  its  mica  remains  unchanged,  and  its 
quartz  forms  the  sand  of  the  clay. 

The  magnetic  and  titanic  oxides  of  iron  existing  in  granite  are 
still  found  in  the  clay  as  peroxide  of  iron  and  titanic  acid. 

The  blue  clays  arise  from  syenite  and  greenstone  ;  for  in  these 
mica  is  absent  (Forchammer). 

The  great  strata  of  clay  at  Halle  have  had  their  origin  in  the 
disintegration  of  porphyry.* 

The  white  basis  of  the  clay  is  easily  distinguished  by  moisten- 
ing it :  while  the  felspar  may  be  recognised  by  its  yellow  color 
(Mitscherlich).  The  silica,  dissolved  by  the  potash,  or  soda,  is 
sometimes  found  deposited  in  a  crystalline  form  on  the  crystals 
of  felspar  ;  this  is  often  observed  in  the  trachyte  of  the  Seven 
Mountains  near  Bonn  (Mitscherlich).  Most  sand-stones  contain, 
mixed  with  them,  silicates  with  alkaline  bases.  In  the  sandstone 
of  the  Holy  Mountain  near  Heidelberg,  many  unchanged  frag- 
ments of  felspar  are  observed,  which  are  partly  changed  into 
clay  and  form  white  points  in  the  sandstone. 

The  analysis  of  the  porcelain  clays  proves  that  the  felspars 
from  which  they  were  formed  have  not  reached  their  utmost 
limit  of  disintegration,  for  they  still  contain  potash.  The  porce- 
lain clays  are  those  which  are  refractory  in  the  fire,  and  do  not 
melt  when  exposed  to  the  strongest  heat  of  our  furnaces.  The 
difficult  fusibility  of  the  porcelain  clays  depends  upon  their 
small  proportion  of  the  alkaline  bases,  potash,  soda,  lime,  mag- 


*The 

decomposed  felspar, 

porcelain  clay 

of 

Mori,   1 

near 

Halle, 

iists  of— 

Silica     - 

- 

. 

71-42 

Alumina 

. 

- 

26-07 

Peroxide  of 

iron     - 

- 

1-93 

Lime 

- 

- 

013 

Potash 0-45 


FORMATION  OF  CLAYS.  61 


nesia,  and  protoxide  of  iron.*  When  we  compare  the  other 
kinds  of  clay  with  the  porcelain  clays,  we  find  that  the  infusible 
clays,  or  clays  poor  in  potash,  are  of  rare  occurrence.  The 
clays  diffused  through  the  most  kinds  of  rocks,  those  occurring 
in  arable  land,  and  those  in  the  beds  of  clay  interspersed  with 
the  layers  of  brown  and  mineral  coal,  contract  when  exposed  to 
heat,  and  become  vitrified  in  a  strong  fire.  Loam  also  melts  in 
a  similar  manner.  When  the  oxides  of  iron  are  not  present  in  the 
clays,  their  fusibility  is  in  direct  proportion  to  the  amount  of  their 
alkaline  ingredients.  Clays  arising  from  the  disintegration  of  the 
potash  felspars,  are  free  from  lime ;  those  formed  from  Labrador 
spar  (the  principal  component  of  basalt  and  lava),  contain  lime 
and  soda. 

The  limestones  containing  much  clay  are  proportionally  the 
richest  in  alkaline  ingredients.  The  marls  and  stones  used  for 
cement  belong  to  this  class  of  minerals.  They  differ  from  other 
limestones  by  possessing  the  property,  after  moderate  burning, 
of  hardening  when  in  contact  with  water.  During  the  burning 
of  marl  and  of  many  other  natural  cements,  the  constituents  of 
the  clay  and  lime  act  chemically  upon  each  other,  giving  rise  to 
an  anhydrous  apophyllite,  or  an  analogous  compound  of  silicate 
of  potash  and  silicate  of  lime,  which,  being  brought  in  contact 
with  water,  forces  the  latter  into  chemical  combination  in  a  man- 
ner similar  to  burnt  gypsum,  and  crystallizes  along  with  it.f 
When  a  fragment  of  chalk  is  moistened  with  a  solution  of  silicate 
of  potash,  the  latter  forms  a  new  compound  on  the  surface,  and 
this  becomes  hard  and  stony.  The  lime  of  the  chalk  takes  the 
place  of  potash  in  the  silicate  of  potash,  and    a   certain   quan- 

*  COMPOSITIOX    OF    PORCELAIN    CI.AYS. 

St.  Yvreux.  Meissen. 

Silica        -         -         -     46S     -         -         -     52-8 
Alumina  -         -     37-3     -         -         -     31-2 

Potash      -         -         -       2-5     -         -         -       2-2 

Schneeberg. 
Silica         -         -         -         -    43-6 
Alumina    -         -         -         -     37"7 
Peroxide  of  iron  -         -       I'D 

Potash  and  water        -         -     12*5 
t  Formula  of  Apophyllite— Ko,  2  Si  O3  +  8  Ca  0,  Si  O  3  +  16  aq 


FORMATION  OF  SOILS. 


tity  of  potash  is  set  at  liberty  in  the  form  of  a  carbonate 
(Kuhlmann), 

The  preceding  considerations  prove  very  clearly  that  arable 
land  has  had  its  origin  in  the  chemical  and  mechanical  actions 
exerted  upon  rocks  and  minerals  rich  in  alkalies  and  alkaline 
earths,  by  which  means  their  coherence  has  been  gradually 
destroyed.  It  is  scarcely  necessary  to  furnish  any  further  proofs 
that  all  clays,  whether  they  be  pure  or  mixed  with  other  minerals, 
so  as  to  form  soils,  suffer  progressive  and  continued  changes. 
These  changes  consist  in  the  giving  of  a  soluble  form  to  the 
alkalies  and  alkaline  bases,  by  the  combined  action  of  water  and 
of  carbonic  acid.  This  gives  rise  to  the  formation  of  soluble 
silicates,  or  if  these  are  decomposed  by-  the  carbonic  acid,  to  the 
hydrate  of  silica,  which,  being  in  its  peculiar  soluble  condition, 
may  be  taken  up  by  the  roots  of  plants. 

The  influence  of  air,  carbonic  acid,  and  moisture,  upon  the 
constituents  of  rocks,  is  best  observed  in  certain  uninhabited  dis- 
tricts of  South  America,  where  huntsmen  and  herds  are  the  dis- 
coverers of  rich  mines  of  silver.  By  the  action  of  the  weather 
the  constituents  of  the  ores  of  silver  are  gradually  dissolved  and 
carried  away  by  winds  and  by  rains ;  the  nobler  metals  resist  the 
destruction  and  remain  on  the  surface.  It  is  well  known  that 
metallic  silver  veins  are  found  in  sharp  angular  projections  from 
the  surface  of  the  rock.* 

*  Darwin  states  that  the  mine  at  Chanuncillo,  from  which  silver  to  the 
value  of  many  hundred  thousand  pounds  sterling  has  been  obtained  in  a 
few  years,  was  discovered  by  a  man  who.  in  throwing  a  stone  after  a  mule, 
found  it  heavier  than  an  ordinary  stone  ;  it  was  a  piece  of  solid  silv<  r,  and 
was  a  fragment  of  a  projecting  vein  of  tlat  metal. 


INSOLUBILITY  OF  HUMUS. 


CHAPTER   IX. 

The  Art  of  Culture. 

The  conditions  necessary  for  the  life  of  all  vegetables  have  been 
considered  in  the  preceding  part  of  the  work.  Carbonic  acid, 
ammonia,  and  water,  yield  elements  for  all  the  organs  of  plants. 
Certain  inorganic  substances — salts  and  metallic  oxides — serve 
peculiar  functions  in  their  organism,  and  many  of  them  must  be 
viewed  as  essential  constituents  of  particular  parts. 

The  atmosphere  and  the  soil  offer  the  same  kind  of  nourish- 
ment to  the  leaves  and  roots.  The  former  contains  a  compara- 
tively inexhaustible  supply  of  carbonic  acid  and  ammonia  ;  the 
latter,  by  means  of  its  humus,  generates  constantly  fresh  carbonic 
acid,  whilst,  during  the  winter,  rain  and  snow  introduce  into  the 
soil  a  quantity  of  ammonia,  sufficient  for  the  development  of  the 
leaves  and  blossoms. 

The  complete,  or  it  may  be  said,  the  absolute  insolubility  in 
cold  water  of  vegetable  matter  in  progress  of  decay  (humus), 
appears  on  closer  consideration  to  be  a  most  wise  arrangement 
of  nature.  For  if  humus  possessed  even  a  smaller  degree  of 
solubility  than  that  ascribed  to  the  substance  called  humic  acid, 
it  must  be  dissolved  by  rain-water.  Thus,  the  yearly  irrigation 
of  meadows  would  remove  a  great  part  of  it  from  the  ground, 
and  a  heavy  and  continued  rain  would  impoverish  a  soil.  But 
humus  is  soluble  only  when  combined  with  oxygen  ;  it  can  be 
taken  up  by  water,  therefore,  only  as  carbonic  acid. 

When  moisture  is  absent,  humus  may  be  preserved  for  cen- 
turies :  but  when  moistened  with  water,  it  converts  the  surround- 
ing oxygen  into  carbonic  acid.  As  soon  as  the  action  of  the  air 
ceases,  that  is,  as  soon  as  it  is  deprived  of  oxygen,  the  humus 
•uffers  no  further  change.  Its  decay  proceeds  only  when  plants 
grow  in  a  soil  containing  it ;  for  they  absorb  by  their  roots  the 


THE  ART  OF  CULTURE. 


carbonic  acid  as  it  is  formed.  But  the  soil  receives  again  from 
living  plants  the  carbonaceous  matter  it  thus  loses,  so  that  the 
proportion  of  humus  in  it  does  not  decrease. 

The  stalactitic  caverns  in  Franconia,  and  those  in  the  vicinity 
of  Baireuth  and  Streitberg,  lie  beneath  a  fertile  arable  soil  ;  the 
abundant  decaying  vegetables  or  humus  in  this  soil,  being  acted 
on  by  moisture  and  air,  constantly  evolve  carbonic  acid,  which 
is  dissolved  by  the  rain.  The  rain-water  thus  impregnated  per- 
meates the  porous  limestone,  which  forms  the  walls  and  roofs  of 
the  caverns,  and  dissolves  in  its  passage  as  much  carbonate  of 
lime  as  corresponds  to  the  quantity  of  carbonic  acid  contained 
in  it.  Water  and  the  excess  of  carbonic  acid  evaporate  from 
this  solution  when  it  has  reached  the  interior  of  the  caverns,  and 
the  limestone  is  deposited  on  the  walls  and  roofs  in  crystalline 
crusts  of  various  forms.  There  are  few  spots  on  the  earth  wh^re 
so  many  circumstances  favorable  to  the  production  of  humate  of 
lime  are  combined,  if  the  humus  actually  existed  in  the  soil  in 
the  form  of  humic  acid.  Decaying  vegetable  matter,  water,  and 
lime  in  solution,  are  brought  together,  but  the  stalactites  formed 
contain  no  humic  acid  ;  they  are  of  a  glistening  white  or  yellow- 
ish color,  in  part  transparent,  like  calcareous  spar,  and  may  be 
heated  to  redness  without  becoming  black. 

The  subterranean  vaults  in  the  old  castles  near  the  Rhine,  in 
the  "  Bergstrass,"  and  in  the  Wetterau,  are  constructed  of  sand- 
stone, granite,  or  basalt,  and  present  appearances  similar  to  the 
limestone  caverns.  The  roofs  of  these  vaults,  or  cellars,  are 
covered  externally  to  the  thickness  of  several  feet  with  vegetable 
mould,  which  has  been  formed  by  the  decay  of  plants.  The  rain 
falling  upon  them,  sinks  through  the  earth,  and  dissolves  the 
mortar  by  means  of  the  carbonic  acid  derived  from  the  mould ; 
and  this  solution  evaporating  in  the  interior  of  the  vaults,  covers 
them  with  small  thin  stalactites,  which  are  quite  free  from  humic 
acid. 

In  such  a  filtering  apparatus,  built  by  the  hand  of  Nature,  we 
have  placed  before  us  the  result  of  experiments  which  have  been 
continued  for  hundreds  or  thousands  of  years.  Now,  if  water 
possessed  the  power  of  dissolving  a  hundred-thousandth  part  of 
its  own  weight  of  humic  acid  or  humate  of  lime,  and  if  humio 


INSOLUBILITY  OF  HUMUS. 


acid  were  present,  we  should  find  the  inner  surface  of  the  roofs 
of  these  vaults  and  caverns  covered  with  these  substances ;  bu/ 
we  cannot  detect  the  smallest  trace  of  them.  We  must  feel  con- 
vinced that  humic  acid  is  absent  both  from  the  soils  of  fields  and 
of  gardens,  when  we  consider  that  humic  acid  gives  to  water  a 
dark  brown  color,  whereas  well  and  spring  water  is  quite  clear 
and  colorless,  and  leaves  after  evaporation  only  a  residue  of  salts 
formed  by  mineral  acids,  without  humic  acid.  The  water  of 
wells  and  of  springs  is  actually  rain-water  which,  in  passing 
through  the  soil,  must  exert  all  its  solvent  action  on  the  humates. 
If  humate  of  potash  existed  in  soils,  all  the  spring  and  river  water 
collected  at  a  certain  depth  ought  to  contain  traces  of  it.  But 
even  the  mineral  waters  from  the  springs  of  Seller  and  Fachin- 
ger,  containing  alkaline  carbonates,  are  destitute  of  a  trace  of 
humic  acid  ;  although  these  waters  arise  in  a  marshy  soil  abound- 
ing in  vegetable  matter.  There  could  scarcely  be  found  more 
clear  and  convincing  proofs  of  the  absence  of  the  humic  acid  of 
chemists  from  common  vegetable  mould. 

The  common  view  adopted  respecting  the  modus  operandi  of 
humic  acid  does  not  afford  any  explanation  of  the  following  phe- 
nomenon : — A  very  small  quantity  of  humic  acid  dissolved  in 
water  gives  to  it  a  yellow  or  brown  color.  Hence  it  would  be 
supposed  that  a  soil  would  be  more  fruitful  in  proportion  as  it 
was  capable  of  giving  this  color  to  water,  that  is,  of  yielding  it 
humic  acid.  But  it  is  very  remarkable  that  cultivated  plants  do 
not  thrive  in  such  a  soil,  and  that  all  manure  must  have  lost  this 
property  before  it  can  exercise  a  favorable  influence  upon  their 
vegetation.  Water  from  barren  peat  soils  and  marshy  meadows, 
upon  which  few  plants  flourish,  contains  much  of  this  humic 
acid  •  but  all  agriculturists  and  gardeners  agree  that  the  most 
suitable  and  best  manure  for  cultivated  plants  is  that  which  has 
completely  lost  the  property  of  giving  a  color  to  water. 

The  soluble  substance,  which  gives  to  water  a  brown  color,  is 
a  product  of  the  putrefaction  of  all  animal  and  vegetable  mat- 
ters ;  its  formation  is  an  evidence  that  there  is  not  oxygen  sufli 
cient  to  begin,  or  at  least  to  complete,  the  decay.  The  brown 
solutions  containing  this  substance  are  decolorized  in  the  air  by 
absorbing  oxygen,  and  a  black  coaly  matter  precipitates — the  sub* 


96  THE  ART  OF  CULTURE. 

stance  named  "  coal  of  humus."  Now  if  a  soil  were  impreg- 
nated with  this  matter,  the  effect  on  the  roots  of  plants  would  be 
the  same  as  that  of  entirely  depriving  the  soil  of  oxygen ;  plants 
would  be  as  little  able  to  grow  in  such  ground  as  they  would  if 
hyd rated  protoxide  of  iron  were  mixed  with  the  soil.  All  plants 
die  in  soils  and  water  destitute  of  oxygen  ;  absence  of  air  acts 
exactly  in  the  same  manner  as  an  excess  of  carbonic  acid. 
Stagnant  water  on  a  marshy  soil  excludes  air,  but  a  renewal  of 
water  has  the  same  effect  as  a  renewal  of  air,  because  water 
contains  it  in  solution.  When  the  water  is  withdrawn  from  a 
marsh,  free  access  is  given  to  the  air,  and  the  marsh  is  changed 
into  a  fruitful  meadow. 

In  a  soil  to  which  air  has  no  access,  or  at  most  but  very  little, 
the  remains  of  animals  and  vegetables  do  not  decay,  for  they  can 
only  do  so  when  freely  supplied  with  oxygen ;  but  they  undergo 
putrefaction,  for  the  commencement  of  which  air  is  present  in 
sufficient  quantity.  Now  putrefixction  is  known  to  be  a  most 
powerful  deoxidizing  process,  the  influence  of  which  extends  to 
all  surrounding  bodies,  even  to  the  roots  and  the  plants  themselves. 
All  substances  from  which  oxygen  can  be  extracted  yield  it  to 
putrefying  bodies  ;  yellow  oxide  of  iron  passes  into  the  state  of 
black  oxide,  sulphate  of  iron  into  sulphuret  of  iron,  &c. 

The  frequent  renewal  of  air  by  ploughing,  and  the  prepara- 
tion of  the  soil,  especially  its  contact  with  alkaline  metallic  ox- 
ides, the  ashes  of  brown  coal,  burnt  lime,  or  limestone,  change 
the  putrefaction  of  its  organic  constituents  into  a  pure  process  of 
oxidation ;  and  from  the  moment  at  which  all  the  organic  matter 
existing  in  a  soil  enters  into  a  state  of  oxidation  or  decay,  its  fer- 
tility is  increased.  The  oxygen  is  no  longer  employed  for  the 
conversion  of  the  brown  soluble  matter  into  the  insoluble  coal  of 
humus,  but  serves  for  the  formation  of  carbonic  acid.  This 
change  takes  place  very  slowly,  and  in  some  instances  the  oxygen 
is  completely  excluded  by  it ;  and  whenever  this  happens,  the 
soil  loses  its  fertility.  Thus,  in  the  vicinity  of  Salzhausen  (a 
village  in  Hesse  Darmstadt,  famed  for  its  mineral  springs),  upon 
the  meadows  of  Griinschwalheim,  unfruitful  spots  are  seen  here 
and  there  covered  with  a  yellow  grass.  If  a  hole  be  bored  from 
twenty  to  twenty-five  feet  deep  in  one  of  these  spots,  carbonic 


IMSOLUBILITY  OF  HUMUS. 


acid  is  emitted  from  it  with  such  violence  that  the  noise  made  by 
the  escape  of  the  gas  may  be  distinctly  heard,  at  the  distance  of 
several  feet.  Here  the  carbonic  acid  rising  to  the  surface  dis- 
places completely  all  the  air,  and  consequently  all  the  oxygen, 
from  the  soil ;  and  without  oxygen  neither  seeds  nor  roots  can  be 
developed  ;  a  plant  will  not  vegetate  in  pure  nitrogen  or  carbonic 
acid  gas. 

Humus  supplies  young  plants  with  nourishment  in  the  form 
of  carbonic  acid  by  the  roots,  until  their  leaves  are  matured 
sufficiently  to  act  as  exterior  organs  of  nutrition  ;  its  quantity 
heightens  the  fertility  of  a  soil  by  yielding  more  nourishment  in 
this  first  period  of  growth,  and  consequently  by  increasing  the 
number  of  organs  of  atmospheric  nutrition.  Humus  acts  in 
this  respect  as  a  source  of  carbon  to  plants  ;  but  vegetable  mould 
contains  other  substances  which  are  equally  necessary  to  plants. 
Vegetable  mould  contains  invariably  carbonate  of  ammonia, 
besides  the  salts  and  alkalies  left  behind  by  the  putrefaction  of 
former  plants.*  Those  plants  which  obtain  their  first  food  from 
the  substance  of  their  seeds,  such  as  bulbous  plants,  could  com- 
pletely dispense  with  humus  ;  its  presence  is  useful  only  in  so  far 
as  it  increases  and  accelerates  their  development,  but  it  is  not 
necessary — indeed,  an  excess  of  it  at  the  commencement  of  their 
growth  is  in  a  certain  measure  injurious. 

The  amount  of  food   capable  of  being  extracted  by  young 

*  Some  vegetable  mould  taken  from  the  interior  of  a  hollow  oak,  yielded 
To'a'o'  of  residue  after  incineration ;  of  this  residue  100  parts  contained  24 
parts  of  soluble  salts  with  alkaline  bases,  10*5  parts  of  earthy  phosphates, 
10  parts  of  earthy  carbonates,  and  32  parts  of  silica.  The  aqueous  extract 
gave  66  per  cent,  of  soluble  salts.  (Saussure.)  One  thousand  parts  of 
the  extract  obtained  by  hot  water  from  vegetable  mould  formed  by  the  de- 
cay of  the  Rhododendron  Fcrrugineum  gave  140  parts  of  ashes,  which 
contained,  according  to  Saussure  : 

Carbonate  of  potash     -     -     -     14 
Chloride  of  potassium       -     -     23 
Siilphate  of  potash       -     -     -     16 
Earthy  phosphates      -     -     -     17*25 
Earthy  carbonates       -     -     -     21  "50 
Silica         -         -  -     -     -       3-25  t 

Metallic  oxides  and  loss  -     -       5"00 
fi 


THE  ART  OF  CULTURE. 


plants  from  the  atmosphere,  in  the  form  of  carbonic  acid  and 
ammonia,  is  limited  ;  they  cannot  assimilate  more  than  the  aif 
contains.  Now,  if  the  quantity  of  their  stems,  leaves,  and 
branches,  has  been  increased  by  the  excess  of  food  yielded  by  the 
soil  at  the  commencement  of  their  development,  they  will  require 
in  a  given  time  for  the  completion  of  their  growth,  and  for  the 
formation  of  their  blossoms  and  fruits,  more  nourishment  from 
the  air  than  it  can  afford,  and  consequently  they  will  not  reach 
maturity.  In  many  cases,  the  nourishiT>snt  afforded  by  the  air 
under  these  circumstances  suffices  only  to  complete  the  forma- 
tion of  the  leaves,  stems,  and  branches.  The  same  result  then 
ensues  as  when  ornamental  plants  are  transplanted  from  the  pots 
in  which  they  have  grown  to  larger  ones,  in  which  their  roots 
are  permitted  to  increase  and  multiply.  All  their  nourishment  is 
employed  for  the  increase  of  their  roots  and  leaves;  they  grow 
luxuriantly,  but  do  not  blossom.  When,  on  the  contrary,  w^ 
take  away  part  of  the  branches,  and  of  course  their  leaves  with 
them,  from  dwarf  trees,  since  we  thus  prevent  the  development 
of  new  branches,  an  excess  of  nutriment  is  artificially  procured 
for  the  trees,  and  is  employed  by  them  in  the  increase  of  the 
blossoms  and  enlargement  of  the  fruit.  It  is  to  effect  this  pur- 
pose that  vines  are  pruned. 

A  new  and  peculiar  process  of  vegetation  ensues  in  all  peren- 
nial plants,  such  as  shrubs,  fruit  and  forest  trees,  after  the  com- 
plete maturity  of  their  fruit.  The  leaves  of  annual  plants  at 
this  period  of  their  growth  change  in  color  ;  while  the  leaves  of 
trees  and  shrubs,  on  the  contrary,  remain  in  activity  until  the 
commencement  of  the  winter.  The  formation  of  the  layers  of 
wood  progresses,  the  wood  becomes  harder  and  more  solid,  but 
afler  August  no  more  new  wood  is  formed  ;  all  the  carbonic  acid 
which  the  plants  now  absorb  is  employed  for  the  production  of 
nutritive  matter  for  the  following  year :  instead  of  woody  fibre, 
starch  is  formed,  and  is  diffused  through  every  part  of  the  plant 
by  the  autumnal  sap  (seve  d'AoAt).*  According  to  the  observa- 
tions of  M.  Heyer,  the  starch  thus  deposited  in  the  body  of  the 
tree  can  be  recognised  in  its  known  form  by  the  aid  of  a  good 

•  Hartlg,  in  Erdmann  und  Schweigger-Seidels  Jourtal,  V  217.    1836. 


EXCESS  OF  NUTRIMENT. 


microscope.  The  barks  of  several  aspens  and  pine-trees*  con- 
tain so  much  substance,  that  it  can  be  extracted  from  them  as 
from  potatoes  by  trituration  with  water.  It  exists  also  in  the 
roots  and  other  parts  of  perennial  plants.  A  very  early  winter, 
or  sudden  change  of  temperature,  prevents  the  formation  of 
this  provision  for  the  following  year  ;  the  wood,  as  in  the  case  of 
the  vine-stock,  does  not  ripen,  and  its  growth  is  in  the  next  year 
very  limited. 

From  the  starch  thus  accumulated,  sugar  and  gum  are  pro- 
duced in  the  succeeding  spring,  while  from  these  the  unnitrogen- 
ized  constituents  of  the  leaves  and  young  sprouts  are  in  their  turn 
formed.  After  potatoes  have  germinated,  the  quantity  of  starch 
in  them  is  found  to  be  diminished.  The  juice  of  the  maple-tree 
loses  sugar  and  ceases  to  be  sweet,  when  its  buds,  blossoms,  and 
leaves  attain  their  maturity. 

The  branch  of  a  willow,  which  contains  a  large  quantity  of 
granules  of  starch  in  every  part  of  its  woody  substance,  puts 
forth  both  roots  and  leaves  in  pure  distilled  or  rain-water  ;  but  in 
proportion  as  it  grows,  the  starch  disappears,  it  being  evidently 
exhausted  for  the  formation  of  the  roots  and  leaves. 

Upon  the  blossoming  of  the  sugar-cane,  likewise,  part  of  the 
sugar  disappears ;  and  it  has  been  ascertained,  that  the  sugar 
does  not  accumulate  in  the  beet-root  until  after  the  leaves  are 
completely  formed. 

These  well-authenticated  observations  remove  every  doubt  as 
to  the  functions  performed  by  sugar,  starch,  and  gum,  in  the  de- 
velopment of  plants ;  and  it  ceases  to  be  enigmatical,  why  these 
three  substances  exercise  no  influence  on  the  growth  or  process 
of  nutrition  of  a  matured  plant,  when  applied  to  it  as  food. 

The  accumulation  of  starch  in  plants  during  the  autumn  has 
been  compared,  although  certainly  erroneously,  to  the  fattening 
of  hibernating  animals  before  their  winter  sleep  ;  but  in  these 
animals  every  vital  function,  except  the  process  of  respiration,  is 
suspended,  and  they  only  require,  like  a  lamp  slowly  burning,  a 
substance  rich  in  carbon  and  hydrogen  to  support  the  process  ot 
combustion  in  the  lungs.     On  their  awaking  from  their  torpor  in 

•  It  is  well  known  that  bread  is  made  from  the  bark  of  pines  in  Sweden 
daring  famines. 


100  THE  ART  OF  CULTURE. 

the  spring,  the  fat  has  disappeared,  but  has  not  served  as  nourish- 
ment. It  has  not  caused  the  least  increase  in  any  part  of  their 
body,  neither  has  it  changed  the  quality  of  any  of  their  organs. 
With  nutrition,  properly  so  called,  the  fat  in  these  animals  has 
not  the  least  connexion. 

The  annual  plants  form  and  collect  their  future  nourishment 
in  the  same  way  as  the  perennial ;  they  store  it  in  their  seeds  in 
the  form  of  vegetable  albumen,  starch  and  gum,  which  are  used 
by  the  germs  for  the  formation  of  their  leaves  and  first  fibres  of 
the  radicle.  The  proper  nutrition  of  the  plants,  their  increase 
in  size,  begins  after  these  organs  are  formed. 

Every  germ  and  every  bud  of  a  perennial  plant  is  the  en- 
grafted embryo  of  a  new  individual,  while  the  nutriment  accu- 
mulated in  the  stem  and  roots  corresponds  to  the  albumen  of 
the  seeds. 

Nutritive  matters  are,  correctly  speaking,  those  substances 
which,  when  presented  from  without,  are  capable  of  sustaining 
the  life  and  all  the  functions  of  an  organism,  by  furnishing  to  the 
different  parts  the  materials  for  the  production  of  their  peculiar 
constituents. 

In  animals,  the  blood  is  the  source  of  the  material  of  the  mus- 
cles and  nerves  ;  by  one  of  its  component  parts,  the  blood 
supports  the  process  of  respiration,  by  others,  the  peculiar  vital 
functions  ;  every  part  of  the  body  is  supplied  with  nourishment 
by  the  blood,  but  its  own  production  is  a  special  function,  without 
which  we  could  not  conceive  life  to  continue.  If  we  destroy  the 
activity  of  the  organs  which  produce  it,  or  if  we  inject  the  blood 
of  one  animal  into  the  veins  of  another,  at  all  events,  if  we  carry 
this  beyond  certain  limits,  death  is  the  consequence. 

The  smallest  particles  of  sugar,  when  left  to  themselves, 
crystallize,  that  is,  they  obey  a  power  strictly  chemical.  It  is 
evident  that  starch  and  woody  fibre  are  more  highly  organized 
compounds  than  sugar,  for  they  possess  a  form  which  they  could 
not  have  obtained  by  the  mere  power  of  cohesion.  We  may 
suppose  that  starch  and  woody  fibre  were  originally  gum  and 
sugar,  or  that  both  have  been  formed  from  sugar ;  but  certain 
conditions  must  be  necessary  for  the  conversion  of  sugar  into 
•tarch,  so  that  it  will  not  be  afliected  when  these  conditions  fail. 


CONDITIONS  ESSENTIAL  TO  NUTRITION  101 

Other  substances  must  be  present  in  a  plant,  bevs-ictes  the  ^stai'oh; 
sugar,  and  gum,  if  these  are  to  take  part  in  the  development  of 
the  germ,  leaves,  and  first  fibres  of  the  radicle.  There  is  no 
doubt  that  a  grain  of  wheat  contains  within  itself  the  component 
parts  of  the  germ  and  of  the  fibres  of  the  radicle.  These  compo- 
nent parts  are  starch  and  gluten  ;  and  it  is  evident  that  neither 
of  them  alone,  but  that  both  simultaneously  assist  in  the  formation 
of  the  root,  for  they  both  suffer  changes  under  the  action  of  air, 
moisture,  and  a  suitable  temperature.  The  starch  is  converted 
into  sugar,  and  the  gluten  also  assumes  a  new  form,  and  both 
acquire  the  capability  of  being  dissolved  in  water,  and  of  thus 
being  conveyed  to  every  part  of  the  plant.  Both  the  starch  and 
the  gluten  are  completely  consumed  in  the  formation  of  the  first 
part  of  the  roots  and  leaves  ;  an  excess  of  either  could  not  be 
used  in  the  formation  of  leaves,  or  in  any  other  way. 

The  conversion  of  starch  into  sugar  during  the  germination  of 
grain  is  ascribed  to  a  vegetable  principle  called  diastase,  which 
is  generated  during  the  act  of  commencing  germination.  But 
this  mode  of  transformation  can  also  be  etfected  by  gluten,  al- 
though it  requires  a  longer  time.  Seeds,  which  have  germinated, 
always  contain  much  more  diastase  thanisnecessary  for  the  conver- 
sion of  their  starch  into  sugar,  for  five  parts  by  weight  of  starch  crxu 
be  converted  into  sugar  by  one  weight  of  malted  barley.  This 
excess  of  diastase  can  by  no  means  be  regarded  as  accidental, 
for,  like  the  starch,  it  aids  in  the  formation  of  the  first  organs  of 
the  young  plant,  and  disappears  with  the  sugar. 

Carbonic  acid,  water,  and  ammonia,  are  the  food  of  fully-d;^- 
veloped  plants  ;  starch,  sugar,  and  gum,  serve,  when  accompanied 
by  an  azotized  substance,  to  sustain  the  embryo,  until  its  first 
organs  of  nutrition  are  unfolded.  The  nutrition  of  a  fcetus  and 
development  of  an  egg  proceed  in  a  totally  different  manner  from 
that  of  an  animal  which  is  separated  from  its  parent;  the  exclu- 
sion of  air  does  not  endanger  the  life  of  the  foetus,  but  would 
certainly  cause  the  death  of  the  independent  animal.  In  the 
same  manner,  pure  water  is  more  advantageous  to  the  growth  of 
a  young  plant  than  that  containing  carbonic  acid,  but  afler  a 
month  the  reverse  is  the  case.     (Saussure.) 

The  formation  of  sugar  in  the  maple-trees  does  not  take  place 


!02  THE  ART  OF  CULTURE. 


iki  the -roots,  but  in  the  woody  substance  of  the  stem.  The 
quantity  of  sugar  in  the  sap  augments  until  it  reaches  a  certain 
height  in  the  stem  of  the  plant,  above  which  point  it  remains 
stationary. 

Just  as  germinating  barley  produces  a  substance  which,  in 
contact  with  starch,  causes  it  to  lose  its  insolubility  and  to  become 
sugar,  so  in  the  roots  of  the  maple,  at  the  commencement  of  vege- 
tation, a  substance  must  be  formed,  which,  being  dissolved  in 
water,  permeates  the  wood  of  the  trunk,  and  converts  into  sugar 
the  starch,  or  whatever  it  may  be,  which  it  finds  deposited  there. 
It  is  certain,  that  when  a  hole  is  bored  into  the  trunk  of  a  maple- 
tree,  just  above  its  roots,  filled  with  sugar,  and  then  closed  again, 
the  sugar  is  dissolved  by  the  ascending  sap.  It  is  further  possi- 
ble that  this  sugar  may  be  disposed  of  in  the  same  manner  as 
that  formed  in  the  trunk;  at  all  events,  it  is  certain  that  the' 
introduction  of  it  does  not  prevent  the  action  of  the  juice  upon 
the  starch  ;  and  since  the  quantity  of  the  sugar  present  is  now 
greater  than  can  be  exhausted  by  the  leaves  and  buds,  it  is  ex- 
creted from  the  surface  of  the  leaves  or  bark.  Certain  diseases 
of  trees,  for  example  that  called  honey-dew,  evidently  depend  on 
the  want  of  the  due  proportion  between  the  quantity  of  the  azo- 
tized  and  that  of  the  unazotized  substances  which  are  applied  to 
them  as  nutriment. 

If  now  we  direct  our  attention  to  the  particular  organs  of  a 
plant,  we  find  every  fibre  and  every  particle  of  wood  surrounded 
by  a  juice  containing  an  azotized  matter ;  while  the  starch, 
granules,  and  sugar,  are  enclosed  in  cells  formed  of  a  substance 
containing  nitrogen.  Indeed  everywhere,  in  all  the  juices  of  the 
fruits  and  blossoms,  we  find  a  substance  destitute  of  nitrogen, 
accompanied  by  one  containing  that  element. 

The  wood  of  the  stem  cannot  be  formed,  qua  wood,  in  the 
leaves,  but  another  substance  must  be  produced  which  is  capable 
of  being  transformed  into  wood.  This  substance  must  be  in  a 
state  of  solution,  and  accompanied  by  a  compound  containing 
nitrogen  ;  it  is  very  probable  that  the  wood  and  the  vegetable 
gluten,  the  starch  granules  and  the  cells  containing  them,  are 
formed  simultaneously,  and  in  this  case  a  certain  fixed  proper. 


CONDITIONS  ESSENTIAL  TO  NUTRITION.  103 

tion  between  them  would  be  a  condition  necessary  for  their 
production. 

In  the  buds  and  young  leaves,  we  find  salts  with  alkaline  bases  ; 
we  find  also  the  azotized  constituents  invariably  accompanied  by 
salts  of  phosphoric  acid  :  we  must,  therefore,  suppose  that  these 
substances  execute  some  functions  necessary  to  the  support  of 
the  vital  processes  of  plants.  We  may  suppose  that,  in  the  ab- 
sence of  certain  constituents  of  the  soil,  the  compounds  of  plants 
containing  nitrogen  and  sulphur  could  not  be  formed,  and  that 
without  the  presence  of  such  compounds  and  of  alkaline  bases, 
carbonic  acid  could  not  be  taken  up  and  decomposed. 

According  to  this  view,  the  assimilation  of  the  substances 
generate'  in  the  leaves  will  (cceteris  paribus)  depend  on  the 
quantity  f  nitrogen  contained  in  the  food.  When  a  sufficient 
quantity  if  nitrogen  is  not  present  to  aid  in  the  assimilation  of 
the  substances  destitute  of  it,  these  substances  will  be  separated 
as  excrements  from  the  bark,  roots,  leaves,  and  branches.  The 
exudations  of  mannite,  gum,  and  sugar,  in  strong  and  healthy 
plants,  cannot  be  ascribed  to  any  other  cause.* 

Analogous  phenomena  are  presented  by  the  process  of  diges- 
tion in  the  human  organism.  In  order  to  restore  the  loss  sus- 
tained by  every  part  of  the  body  in  the  processes  of  respiration 
and  perspiration,  the  organs  of  digestion  require  to  be  supplied 
with  food,  consisting  of  substances  containing  nitrogen  and  of 
others  destitute  of  it,  in  definite  proportion,  and  also  with  certain 
mineral  substances  to  effect  their  transformation  into  blood.  If 
tlie  substances  d<  ?titute  of  nitrogen  preponderate,  either  they 
n^ill  be  expended  in  the  formation  of  fat,  or  they  will  pass  un- 
jhanged  through  the  organism.      This  is  particularly  observed 

*  M.  Trapp,  in  Giessen,  possesses  a  Clerodendron  fragrans  growing  in 
the  house ;  it  exudes  on  the  surface  of  its  leaves,  in  September,  large 
colorless  drops,  which  form  regular  crystals  of  sugar-candy  upon  drying  ; — 
I  am  not  aware  whether  the  juice  of  this  plant  contains  sugar.  Langlois 
has  lately  observed,  during  the  dry  summer  in  1842,  that  the  leaves  of  the 
linden-tree  became  covered  with  a  thick  and  sweet  liquid,  in  such  quan- 
tity, that  for  several  hours  of  the  day  it  ran  off  the  leaves  like  drops  of 
rain.  Many  kilogrammes  might  have  been  collected  from  a  moderately- 
sized  linden-tree.  This  sweet  juice  contained  principally  grape  sugar  and 
mannite.     (^Annales  de  Chimie  et  Phytique,  iii.  Serie,  tom.  vii.,  p.  34&^ 


104  THE  ART  OF  CULTURE. 

in  those  people  who  live  almost  exclusively  upon  potatoes;  tbeii 
excrements  contain  a  large  quantity  of  unchanged  granules  of 
starch.  Potatoes,  which,  when  mixed  with  hay  alone,  are 
scarcely  capable  of  supporting  the  strength  of  a  horse,  form  with 
bread  and  oats  a  strong  and  wholesome  fodder. 

It  will  be  evident  from  the  preceding  considerations,  that  the 
products  generated  by  a  plant  may  vary  exceedingly  according 
to  the  substances  given  it  as  food.  A  superabundance  of  carbon 
in  the  state  of  carbonic  acid  conveyed  through  the  roots  of  plants, 
without  being  accompanied  by  nitrogen,  cannot  be  converted 
either  into  gluten,  albumen,  or  wood  ;  but  either  it  will  be  sepa- 
rated in  the  form  of  excrements,  such  as  sugar,  starch,  oil,  wax, 
resin,  mannite,  or  gum,  or  these  substances  will  be  deposited  in 
greater  or  less  quantity  in  the  wide  cells  and  vessels. 

The  quantity  of  gluten,  and  of  vegetable  albumen,  will 
augment  when  plants  are  supplied  with  an  excess  of  food  con- 
taining nitrogen,  if  certain  otiier  conditions  be  fulfilled  ;  and 
ammoniacal  salts  will  remain  in  the  sap,  when,  for  example,  as 
in  the  culture  of  the  beet,  we  manure  the  soil  with  a  highly 
nitrogenous  substance,  or  when  we  suppress  the  functions  of  the 
leaves  by  removing  them  from  the  plant. 

We  know  that  the  ananas  is  scarcely  eatable  in  its  wild  state, 
and  that  it  shoots  forth  a  great  quantity  of  leaves  when  treated 
with  rich  animal  manure,  without  the  fruit  on  that  account  ac- 
quiring a  larger  amount  of  sugar ;  that  the  quantity  of  starch  in 
potatoes  increases  when  the  soil  contains  much  humus,  but  de- 
creases when  the  soil  is  manured  with  strong  animal  manure, 
although  then  the  number  of  cells  increases,  the  potatoes  acquir- 
ing in  the  first  case  a  mealy,  in  the  second  a  soapy,  consistence. 
Beet-roots  taken  from  a  barren  sandy  soil,  contain  a  maximum 
of  sugar,  and  no  ammoniacal  salts;  and  the  Teltowa  parsnip 
loses  its  mealy  state  in  a  highly  manured  land,  because  there 
all  the  circumstances  necessary  for  the  formation  of  cells  are 
united. 

An  abnormal  production  of  certain  component  parts  of  plants 
presupposes  a  power  and  capability  of  assimilation  to  which  the 
most  powerful  chemical  action  cannot  be  compared.  The  best 
idea  of  it  may  be    formed  by  considering   that  it  surpasses  in 


EFFECT  OF  LIGHT  ON  CHEMICAL  COMBINATION.        lOJ 

power  the  strongest  galvanic  battery,  with  which  we  are  not  able 
to  separate  the  oxygen  from  carbonic  acid.  The  affinity  of 
chlorine  for  hydrogen,  and  its  power  of  decomposing  water  under 
the  influence  of  light,  and  of  setting  at  liberty  its  oxygen,  cannot 
be  considered  as  at  all  equalling  the  power  and  energy  with 
which  a  leaf  separated  from  a  plant  decomposes  the  carbonic 
acid  absorbed  by  it. 

In  living  plants  and  in  their  seeds,  there  exists  a  peculiar 
power  different  from  all  other  causes  of  increase  of  mass.  This 
power,  however,  only  shows  itself  in  action  when  aided  by  the 
influence  of  heat  or  of  light.  In  spring,  when  the  heat  of  the  sun 
penetrates  the  earth,  the  asparagus  may  put  forth  shoots  of 
many  feet  in  length  quite  independently  of  the  action  of  light. 
But  the  constituents  of  these  shoots  were  formerly  constituents 
of  the  roots.  A  conversion  of  pre-existing  compounds  into  new 
products,  and  their  assumption  of  new  forms,  can  proceed  with- 
out light,  although  not  without  heat.  But  this  is  not  a  true  in- 
crease of  mass,  or  an  increase  in  the  quantity  of  carbon.  The 
latter  process  only  takes  place  under  the  influence  of  light. 

The  common  opinion  that  only  the  direct  solar  rays  can  effect 
the  decomposition  of  carbonic  acid  in  the  leaves  of  plants,  and 
that  reflected  or  diffused  light  does  not  possess  this  property^  is 
wholly  an  error,  for  exactly  the  same  constituents  are  generated 
in  a  number  of  plants,  whether  the  direct  rays  of  the  sun  fall 
upon  them,  or  whether  they  grow  in  the  shade.  They  require 
light,  and  indeed  sun-light,  but  it  is  not  necessary  that  the  direct 
rays  of  the  sun  should  reach  them.  Their  functions  certainly 
proceed  with  greater  intensity  and  rapidity  in  sunshine  than  in 
the  diffused  light  of  day  ;  but  there  is  nothing  more  in  this  than 
the  similar  action  which  light  exercises  on  ordinary  chemical 
combinations  ;  it  merely  accelerates  in  a  greater  or  less  degree 
the  action  already  subsisting. 

Thus  chlorine  and  hydrogen  combining  form  muriatic  acid. 
This  combination  is  effected  in  a  few  hours  in  common  daylight, 
but  it  ensues  instantly,  with  a  violent  explosion,  under  exposure 
to  the  direct  solar  rays,  whilst  not  the  slightest  change  in  the 
two  gases  takes  place  in  perfect  darkness.  When  the  oil  formed 
from  defiant  gas  is  exposed  in  a  vessel  with  chlorine  gas  to  the 


106  THE  ART  OF  CULTURE. 

direct  solar  rays,  chloride  of  carbon  is  immediately  produced  ; 
but  the  same  compound  can  be  obtained  with  equal  facility  in 
the  diffused  ligh  of  day,  a  longer  time  only  being  required. 
When  this  experiment  is  performed  in  the  way  first  mentioned, 
two  products  only  are  observed  (muriatic  acid  and  perchloride 
of  carbon) ;  whilst  by  the  latter  method  a  class  of  intermediate 
bodies  are  produced,  in  which  the  quantity  of  chlorine  constantly 
augments,  until  at  last  the  whole  oil  is  converted  into  the  same 
two  products  as  in  the  first  case.  Here,  also,  not  the  slightest 
trace  of  decomposition  takes  place  in  the  dark.  Nitric  acid  is 
decomposed  in  common  daylight  into  oxygen,  and  peroxide  of 
nitrogen  ;  and  chloride  of  silver  becomes  black  in  the  diffused 
light  of  day,  as  well  as  in  the  direct  solar  rays  ; — in  short,  all 
actions  of  a  similar  kind  proceed  in  the  same  way  in  diffused 
light  as  well  as  in  the  solar  light,  the  only  difference  consisting, 
in  the  time  in  which  they  are  effected.  It  cannot  be  otherwise 
in  plants,  for  the  mode  of  their  nutriment  is  the  same  in  all, 
with  the  exception  of  certain  parasites  which  obtained  their  car- 
bon, either  not  at  all,  or  only  partially,  from  the  original  source  ; 
and  their  component  substances  afford  proof  that  their  food  has 
suffered  absolutely  the  same  change,  whether  they  grow  in  the 
sunshine  or  in  the  shade.* 

All  the  carbonic  acid,  therefore,  which  we  supply  to  a  plant 
will  undergo  a  transformation,  provided  its  quantity  be  not 
greater  than  can  be  decomposed  by  the  leaves.  We  know  that 
an  excess  of  carbonic  acid  kills  plants,  but  we  know  also  that 
nitrogen  to  a  certain  degree  is  not  essential  for  the  decomposition 
of  carbonic  acid.  All  the  experiments  hitherto  instituted  prove, 
that  fresh  leaves  placed  in  water  impregnated  with  carbonic 
acid,  and  exposed  to  the  influence  of  solar  light,  emit  oxygen 

*  The  impossibility  of  bringing  to  blossom  and  seed  mosses  and  other 
cryptogamous  plants,  in  ordinary  daylight,  induced  Mr.  Noller,  an  excel- 
lent botanist  and  chemist  in  Darmstadt,  to  form  the  opinion  that  the  green 
light  from  the  leaves  formed  a  necessary  condition  of  their  life.  He 
planted  numerous  kinds  of  these  plants  in  mouldered  wood  placed  in  little 
glass  tubes,  and  covered  the  whole  with  a  green  glass  globe.  The  experi- 
ment established  his  view  in  a  beautiful  manner.  All  these  elegant  plants 
developed  under  these  conditions  with  the  greatest  luxuriance,  and  put 
forth  both  blossoms  and  seeds 


IMPORTANCE  OF  AGRICULTURE.  lOT 

gas,  whilst  the  carbonic  acid  disappears.  Now  in  these  experi- 
ments no  nitrogen  :^  supplied  at  the  same  time  with  the  carbonic 
acid  ;  hence  no  other  conclusion  can  be  drawn  from  them  than 
that  a  simultaneous  introduction  of  nitrogen  is  not  necessary  for 
the  decomposition  of  carbonic  acid, — for  the  exercise,  therefore, 
of  one  of  the  functions  of  plants.  And  yet  the  presence  of  a 
substance  containing  this  element  appears  to  be  indispensable  for 
the  assimilation  of  the  products  newly  formed  by  the  decomposi- 
tion of  the  carbonic  acid,  and  their  consequent  adaptation  for  en- 
tering into  the  composition  of  the  different  organs. 

The  carbon  abstracted  from  the  carbonic  acid  acquires  in  the 
leaves  a  new  form,  in  which  it  is  soluble  and  transferable  to  all 
parts  of  the  plant.  In  this  new  form  the  carhop  aids  in  consti- 
tuting several  new  products ;  these  are  named  sugar  when  they 
possess  a  sweet  taste,  gum  or  mucilage  when  tasteless,  and  ex- 
cremcntitious  matters  when  expelled  by  the  roots  or  other  parts. 

Hence  it  is  evident  that  the  quantity  and  quality  of  the  sub- 
stances generated  by  the  vital  processes  of  a  plant  will  vary 
according  to  the  proportion  of  the  different  kinds  of  food  with 
which  it  is  supplied.  The  development  of  every  part  of  a  plant 
in  a  free  and  uncultivated  state  depends  on  the  amount  and  na- 
ture of  the  food  afforded  to  it  by  the  spot  on  which  it  grows.  A 
plant  is  developed  on  the  most  sterile  and  unfruitful  soil  as  well 
as  on  the  most  luxuriant  and  fertile;  the  only  difference  which 
can  be  observed  being  in  its  J.'cight  and  size,  in  the  number  of 
its  twigs,  branches,  leaves,  blossoms,  and  fruit.  Whilst  the  indi- 
vidual organs  of  a  plant  increase  on  a  fertile  soil,  they  diminish 
on  another  where  those  substances  which  are  necessary  for  their 
formation  are  not  so  bountifully  supplied  ;  and  the  proportion  of 
the  constituents  containing  nitrogen,  and  those  destitute  of  it, 
varies  with  the  amount  of  nitrogenous  matter  in  the  food  of  plants. 

The  development  of  the  stem,  leaves,  blossoms,  and  fruit  of 
plants,  is  dependent  on  certain  conditions,  the  knowledge  of  which 
enables  us  to  exercise  some  influence  on  certain  of  their  internal 
constituents  as  well  as  on  their  size.  It  is  the  duty  of  the  natural 
philosopher  to  discover  what  these  conditions  are  ;  for  the  funda- 
mental principles  of  agriculture  must  be  based  on  a  knowledge 
of  them.     There  is  no  profession  which  can  be  compared  in 


108  THE  ART  OF  CULTURE. 


importance  with  that  of  agriculture,  for  to  it  bebngs  the  produc- 
tion of  food  for  man  and  for  animals ;  on  it  depends  the  welfare 
and  development  of  the  whole  human  species,  the  riches  of  states, 
and  all  industry,  manufacturing  and  commercial.  There  is  hO 
profession  in  which  the  apptication  of  correct  principles  is  pro- 
ductive of  more  beneficial  eifects,  or  is  of  greater  and  more 
decided  influence.  Hence  it  appears  quite  unaccountable,  that 
we  may  vainly  search  for  one  leading  principle  in  the  writings 
of  agriculturists  and  vegetable  physiologists. 

The  methods  employed  in  the  cultivation  of  land  are  different 
in  every  country,  and  in  every  district ;  and  when  we  inquire 
the  causes  of  these  differences,  we  receive  the  answer  that  they 
depend  upon  circumstances.  (Les  circonstances  font  les  assole- 
ments.)     No  ansvter  could  show  ignorance  more  plainly. 

In  addition  to  the  general  conditions,  such  as  heat,  light,  mois- 
ture, and  the  component  parts  of  the  atmosphere,  all  of  which 
are  necessary  lor  the  growth  of  all  plants,  certain  substances 
are  found  to  exercise  a  peculiar  influence  on  their  development. 
These  substances  either  are  already  contained  in  the  soil,  or  are 
supplied  to  it  in  the  form  of  the  matters  known  under  the  general 
name  of  manure.  But  what  does  the  soil  contain,  and  what  are 
the  components  of  the  substances"  used  as  a  manure?  Until 
these  points  are  satisfactorily  determined,  a  rational  system  of 
agriculture  cannot  exist.  The  power  and  knowledge  of  the 
physiologistj  of  the  agriculturist  and  chemist,  must  be  united 
for  the  complete  solution  of  these  questions;  and,  in  order  to 
attain  this  end,  a  commencement  must  be  made. 

The  GENERAL  object  of  agriculture  is  to  produce  in  the  most 
advantageous  manner  certain  qualities,  or  a  maximum  size,  in 
certain  parts  or  organs  of  particular  plants.  Now, "  this  object 
can  be  attained  only  by  the  application  of  our  knowledge  of  such 
substances  as  we  know  to  be  indispensable  to  the  development  of 
these  parts  or  organs,  or  by  supplying  the  conditions  necessary 
to  the  production  of  the  qualities  desired. 

The  rules  of  a  rational  system  of  agriculture  should  enable 
us,  therefore,  to  give  to  each  plant  that  which  it  specially  requires 
for  the  attainment  of  the  object  in  view. 

The  SPECIAL  object  of  agriculture  is  to  obtain  an  abnormal 


OBJECTS  OF  AGRICaLTURE.  lOd 

development  and  production  of  certain  parts  of  plants,  or  of 
certain  vegetable  matters,  employed  as  food  for  man  and  animals^ 
or  for  the  purposes  of  industry. 

i'iie  means  employed  vary  according  to  the  objects  which  it 
is  desired  to  attain.  Thus,  the  mode  of  culture  employed  for 
the  purpose  of  procuring  fine  pliable  straw  for  Tuscan  hats,  is 
the  very  opposite  to  that  which  must  be  adopted  in  order  to  pro- 
duce a  maximum  of  corn  from  the  same  plant.  Peculiar 
methods  must  be  used  for  the  production  of  nitrogen  in  the 
seeds,  others  for  giving  strength  and  solidity  to  the  straw,  and 
others  again  must  be  followed  when  we  wish  to  give  such 
strength  and  solidity  to  the  straw  as  will  enable  it  to  bear  the 
weight  of  the  ears. 

We  must  proceed  in  the  culture  of  plants  in  precisely  the 
same  manner  as  we  do  in  the  fattening  of  animals.  The  flesh 
of  the  stag  and  roe,  or  of  wild  animals  in  general,  is  quite  devoid 
of  fat,  like  the  muscular  flesh  of  the  Arab;  or  it  contains  only 
small  quantities  of  it.  Tiie  production  of  flesh  and  fat  may  be 
artificially  increased  ;  for  all  domestic  animals  become  fat.  We 
give  to  animals  food  which  increases  the  activity  of  certain  organs, 
and  is  itself  capable  of  being  transformed  into  fat.  We  add  to 
the  quantity  of  food,  or  we  lessen  the  processes  of  respiration 
and  perspiration  by  preventing  motion. 

The  increase  or  diminution  of  the  vital  activity  of  vegetables 
depends  only  on  heat  and  solar  light,  wiiich  we  have  not  arbitra- 
rily at  our  disposal :  all  that  we  can  do  is  to  supply  substances 
adapted  for  assimilation  by  the  power  already  present  in  the  or- 
gans of  the  plant.  But  what  then  are  these  substances  ?  They 
may  easily  be  detected  by  the  examination  of  a  soil  always  fer- 
tile in  the  existing  cosmical  and  atmospheric  conditions ;  for  it 
is  evident  that  the  knowledge  of  its  state  and  composition  must 
enable  us  to  discover  the  conditions  under  which  such  a  soil  is 
rendered  fertile.  It  is  the  duty  of  the  chemist  to  explain  the 
composition  of  a  fertile  soil,  but  the  discovery  of  its  proper  phy- 
sical state  or  condition  belongs  to  the  agriculturist ;  our  present 
business  lies  only  with  the  former. 

Arable  land  is  originally  formed  by  the  crumbling  of  rocks, 
and  its  properties  depend  on  the  nature  of  their  principal  compo« 


no  THE  ART  OF  CULTURE. 

nent  parts.  Sand,  clay,  and  lime,  are  the  names  given  to  the 
principal  constituents  of  the  different  kinds  of  soil. 

Pure  sand  and  pure  limestones,  in  which  there  are  no  other 
inorganic  substances  except  siliceous  earth,  carbonate  or  silicate 
of  lime,  form  absolutely  barren  soils.  But  argillaceous  earths 
form  always  a  part  of  fertile  soils.  Now,  from  whence  come 
the  argillaceous  earths  in  arable  land,  what  are  their  constituents, 
and  what  part  do  they  play  in  favoring  vegetation  ?  They  are 
produced  by  the  disintegration  of  aluminous  minerals,  among 
which  the  common  potash  and  soda  felspars,  Labrador  spar,  mica, 
and  the  zeolites,  are  those  which  most  commonly  undergo  this 
change.  These  minerals  are  found  mixed  with  other  substances 
in  granite,  gneiss,  mica-slate,  porphyry,  clay-slate,  grauwacke 
and  the  volcanic  rocks,  basalt,  clinkstone,  and  lava.  As  mem- 
bers of  the  grauwacke  series  we  have  pure  quartz,  clay-slate, 
and  lime  ;  in  the  sand-stones,  quartz  and  loam.  The  transition 
limestone  and  the  dolomites  contain  an  intermixture  of  clay, 
felspar,  porphyry,  and  clay-slate  ;  and  the  mountain  limestone  is 
remarkable  for  its  quantity  of  argillaceous  earths.  Jura  lime- 
stone contains  3 — 20,  that  of  the  Wurtemburg  Alps  45 — 50  per 
cent,  of  these  earths.  And  in  the  muschelkalk  and  in  the  cal- 
caire  grassier  they  exist  in  greater  or  less  quantity. 

It  is  thus  obvious  that  the  aluminous  minerals  are  the  most 
widely  diffused  on  the  surface  of  the  earth,  and,  as  we  have 
already  mentioned,  they  are  never  absent  from  fertile  soils ; 
and,  if  they  should  happen  to  be  absent  in  soils  capable  of  culti- 
vation, this  only  happens  when  certain  of  their  constituents  are 
supplied  by  other  sources.  Argillaceous  earth  must,  therefore, 
contain  something  which  enables  it  to  exercise  an  influence  on 
the  life  of  plants,  and  to  assist  in  their  development.  The  pro- 
perty on  which  this  depends  is  that  of  its  invariably  containing 
alkalies  and  alkaline  earths,  with  sulphates  and  phosphates. 

Alumina  exercises  only  an  indirect  influence  on  vegetation,  by 
its  power  of  attracting  and  of  retaining  water  and  ammonia  ;  it 
is  itself  very  rarely  found  in  the  ashes  of  plants,*  but  silica  is 

*  Hydrate  of  alumina,  when  mixed  with  extract  of  humus,  decolorizes 
this  substance  and  renders  insoluble  the  coloring  matter.  ( Wiegmann 
und  Polatorf  \ 


FERTILITY  OF  DIFFERENT  SOILS.  Ill 


often  present,  having  in  most  cases  entered  the  plants  by  means 
of  alkalies.  In  order  to  form  a  distinct  conception  of  the  quan- 
tities of  alkalies  in  aluminous  minerals,  it  must  be  remembered 
that  felspar  contains  17J  per  cent,  of  potash,  albite  11*43  per 
cent,  of  soda,  and  mica  3 — 5  per  cent. : — and  that  zeolites  con- 
tain, on  an  average,  13 — 16  per  cent,  of  alkalies.*  The  late 
analyses  of  Ch.  Gmelin,  Lowe,  Fricke,  Meyer,  and  Redten- 
bacher,  have  also  shown,  that  basalt  and  clinkstone  contain  from 
3  to  3  per  cent,  of  potash,  and  from  5 — 7  per  cent,  of  soda ;  that 
clay-slate  contains  from  2-75 — 3-31  per  cent,  of  potash,  and 
loam  from  1^ — 4  per  cent,  of  potash. 

If,  now,  we  calculate  from  these  data,  and  from  the  specific 
weights  of  the  different  substances,  how  much  potash  must  be 
contained  in  a  layer  of  soil,  formed  by  the  disintegration  of  26,- 
910  square  feet  (1  Hessian  acre)  of  one  of  these  rocks  to  the 
depth  of  20  inches,  we  find  that  a  soil  derived  from 

Felspar  contains            -          -  1,152,000  lbs. 

Clinkstone  **         from  200,000  to  400,000    " 

Basalt  "            "       47,500  "  75,000   " 

Clay-slate  "            "     100,000  "  200,000   " 

Loam  "            "       87,000  "  300,000    " 

The  alkalies,  potash,  and  soda,  are  present  in  all  clays  ;  at 
least,  they  have  been  found  in  all  the  argillaceous  earths  in 
which  they  have  been  sought.  The  fact  that  they  contain  potash 
may  be  proved  in  the  clays  of  the  transition  and  stratified  moun- 
tains, as  well  as  in  the  recent  formations  surrounding  Berlin,  by 
simply  digesting  them  with  sulphuric  acid,  by  which  process 
alum  is  formed.  (Mitscherlich.)  It  is  well  known  also  to  all 
manufacturers  of  alum,  that  the  leys  contain  a  certain  quantity 
of  this  salt  ready  formed,  the  potash  of  which  has  its  origin  from 
the  ashes  of  the  stone  and  brown  coal,  which  .'ontains  much 
argillaceous  earth. 

A  thousandth  part  of  loam  mixed  with  the  quartz  in  new  red 
sandstone,  or  with  the  lime  in  the  different  limestone  formations, 
af!brds  as  much  potash  to  a  soil  only  twenty  inches  in  depth  as 
is  sufficient  to  supply  a  forest  of  pines  growing  upon  it  for  a 

•  Recent  investigations  have  shown  that  potash  felspars  always  contain 
a  certain  quantity  of  soda,  and  that  scida  felspars  always  contain  potash. 


il2  THE  ART  OF  Ct3LTURE. 

century.  A  single  cubic  foot  of  felspar  is  sufficient  to  supply  an 
oak  copse,  covering  a  surface  of  26,910  square  feet,  with  the 
potash  required  for  five  years. 

Land  of  the  greatest  fertility  contains  argillaceous  earths  and 
other  's'ntegrated  minerals,  with  chalk  and  sand  in  such  a  pro- 
portion .s  to  give  free  access  to  air  and  moisture.  The  land  in 
the  \ichi'.  V  of  Vesuvius  may  be  considered  as  the  type  of  a  fer- 
tile soil,  aik.  its  fertility  is  greater  or  less  in  different  parts,  ac- 
cording to  iis  proportion  of  clay  or  sand. 

This  soil  being  derived  from  the  disintegration  of  lava,  cannot 
possibly,  owing  to  its  origin,  contain  the  smallest  trace  of  vege- 
table matter  ;  yet  every  one  knows  that  when  lava  or  volcanic 
ashes  have  been  exposed  for  a  time  to  the  influence  of  air  and 
moisture,  all  kinds  of  plants  grow  in  them  with  the  utmost  luxu- 
riance. 

This  fertility  of  lava  is  owing  to  the  alkalies,  alkaline  earths, 
and  silica,  contained  in  it,  which  by  exposure  to  the  weather  are 
rendered  capable  of  being  absorbed  by  plants.  Thousands  of 
years  have  been  necessary  to  convert  stones  and  rocks  into  the 
soil  of  arable  land,  and  thousands  of  years  more  will  be  requisite 
for  their  perfect  reduction,  that  is,  for  the  complete  exhaustion  of 
their  alkalies. 

We  see  from  the  composition  of  the  water  in  rivers,  streamlets, 
and  springs,  how  little  alkali  the  rain-water  is  able  to  extract 
from  a  soil,  even  after  a  term  of  years ;  this  water  is  generally 
soft,  and  the  common  salt,  which  even  the  softest  invariably  con- 
tains, proves  that  the  alkaline  salts,  which  are  carried  to  the  sea 
by  rivers  and  streams,  are  returned  again  to  the  land  by  wind 
and  by  rain. 

Let  us  suppose  that  a  soil  has  been  formed  by  the  action  of 
the  weather  on  the  component  parts  of  granite,  grauwacke,  moun- 
tain limestone,  or  porphyry,  and  that  the  vegetation  upon  it  has 
remained  the  same  for  thousands  of  years.  Now  this  soil  would 
become  a  magazine  of  alkalies  in  a  condition  favorable  for  their 
assimilation  by  the  roots  of  plants. 

The  interesting  experiments  of  Struve  have  proved  that  wate? 
impregnated  with  carbonic  acid  decomposes  rocks  containing 
alkalies,  and  then  dissolves  a  part  of  the  alkaline  carbonates. 


DISINTEGRATION  OF  SOILS.  1J3 

It  is  evident  that  plants  also,  by  producing  carbonic  acid  during 
their  decay,  and  by  means  of  the  acids  which  exude  from  their 
roots  in  the  living  state,  contribute  no  less  powerfully  to  destroy 
the  coherence  of  rocks.  Next  to  the  action  of  air,  water,  and 
change  of  temperature,  plants  themselves  are  the  most  powerful 
agents  in  effecting  the  disintegration  of  rocks. 

Air,  water,  and  ohange  of  temperature  prepare  the  different 
species  of  rocks  for  yielding  to  plants  their  alkalies.  A  soil  ex- 
posed for  centuries  to  all  the  influences  which  effect  the  disinte- 
gration of  rocks,  but  from  which  the  alkalies,  thus  rendered 
soluble,  have  not  been  removed,  will  be  able  to  afford,  during 
many  years,  the  means  of  nourishment  to  vegetables  requiring  a 
considerable  amount  of  alkalies  for  their  growth ;  but  it  must 
gradually  become  exhausted,  unless  those  alkalies  which  have 
been  removed  are  again  replaced  ;  a  period,  therefore,  will  arrive 
when  it  will  be  necessary  to  expose  it  from  time  to  time  to  a 
further  disintegration,  in  order  to  obtain  a  new  supply  of  soluble 
alkalies.  For,  small  as  is  the  quantity  of  alkali  essential  to 
plants,  it  is  nevertheless  quite  indispensable  for  their  perfect  de- 
velopment. But  when  one  or  more  years  have  elapsed  without 
the  removal  of  any  alkalies  from  the  soil,  a  new  harvest  may  be 
expected. 

The  first  colonists  of  Virginia  found  a  soil  similar  to  that 
mentioned  above  ;  harvests  of  wheat  and  tobacco  were  obtained 
for  a  century  from  one  and  the  same  field,  without  the  aid  of 
manure  ;  but  now  whole  districts  are  abandoned  and  converted 
into  unfruitful  pasture-land,  which  without  manure  produces 
neither  wheat  nor  tobacco.  From  every  acre  of  this  land  there 
were  removed  in  the  space  of  one  hundred  years  12,000  lbs.  of 
alkalies  in  leaves,  grain,  and  straw ;  it  became  unfruitful  there- 
fore, because  it  was  deprived  of  every  particle  of  alkali  fit  for 
assimilation,  and  because  that  which  wais  rendered  soluble  again 
in  the  space  of  one  year  was  not  sufiicient  to  satisfy  the  demands 
of  the  plants.  Almost  all  the  cultivated  land  in  Europe  is  in 
this  condition  ;  fallow  is  the  term  applied  to  land  left  at  rest  for 
further  disintegration.  It  is  the  greatest  possible  mistake  to  sup. 
pose  that  the  temporary  diminution  of  fertility  in  a  soil  is  owing 


114  THE  ART  OF  CULTURE. 

to  the  loss  of  humus  ;  it  is  the  mere  consequence  ot*  the  exhaus- 
tion of  alkalies,  and  of  other  essential  ingredients. 

Let  us  consider  the  condition  of  the  country  around  Naples, 
which  is  famed  for  its  fruitful  corn-land  ;  the  farms  and  villages 
are  situated  from  eighteen  to  twenty-four  miles  distant  from  one 
another,  and  between  them  there  are  no  rq^ds,  and  consequently 
no  transportation  of  manure.  Now  corn  has  been  cultivated  on 
this  land  for  thousands  of  years,  without  any  part  of  that  which 
is  annually  removed  from  the  soil  being  artificially  restored  to  it. 
How  can  any  influence  be  ascribed  to  humus  under  such  cir- 
cumstances, when  it  is  not  even  known  whether  humus  was  ever 
contained  in  the  soil  ? 

The  method  of  culture  in  that  district  completely  explains  the 
permanent  fertility.  It  appears  very  bad  in  the  eyes  of  our 
agriculturists,  but  there  it  is  the  best  plan  that  could  be  adopt- 
ed. A  field  is  ploughed  once  every  three  years,  and  is  in  the 
intervals  allowed  to  serve  as  a  sparing  pasture  for  cattle.  The 
soil  experiences  no  change  in  the  two  years  during  which  it  lies 
fallow,  further  than  that  it  is  exposed  to  the  influence  of  the 
weather,  by  which  a  fresh  portion  of  its  alkalies  is  again  set 
free  or  rendered  soluble.  The  animals  fed  on  these  fields  yield 
nothing  to  them  which  they  did  not  formerly  possess.  The  weeds 
upon  which  the  cattle  live  spring  froni  the  soil,  and  the  materials 
returned  to  it  in  the  form  of  excrements  must  always  be  less  in 
quantity  than  those  removed  as  food.  The  fields,  therefore,  can 
have  gained  nothing  from  the  mere  feeding  of  cattle  upon  them  ; 
on  the  contrary,  the  soil  must  have  lost  some  of  its  constituents. 

Experience  has  shown  in  agriculture  that  wheat  should  not  be 
cultivated  after  wheat  on  the  same  soil,  for  it,  as  well  as  tobacco, 
is  of  the  class  of  plants  which  exhaust  a  soil.  But  if  the  humus 
of  a  soil  gives  it  the  power  of  producing  corn,  how  happens  it 
that  wheat  does  not  thrive  in  many  parts  of  Brazil,  where  the 
soils  are  particularly  rich  in  this  substance,  or  in  our  own  climate, 
in  soils  formed  of  mouldered  wood  ;  that  its  stalk  under  these 
circumstances  attains  no  strength,  and  droops  prematurely  ?  The 
cause  is  this,  that  the  strength  of  the  stalk  is  due  to  silicate  of 
potash,  and  that  the  com  requires  certain  phosphates,  and  these 
substances  a  soil  of  humus  cannot  afford,  since  it  does  not  contain 


COMPOSITION  OF  SOILS.  us 


them  ;  the  plant  may,  indeed,  under  such  circumstances,  become 
a  herb,  but  will  not  bear  fruit. 

Again,  how  does  it  happen  that  wheat  does  not  flourish  on  a 
sandy  soil,  and  that  a  calcareous  soil  is  also  unsuitable  for  its 
growth,  unless  it  be  mixed  with  a  considerable  quantity  of  clay  ? 
It  is  because  these  soils  do  not  contain  alkalies  and  certain  other 
ingredients  in  sufficient  quantity,  the  growth  of  wheat  being  ar- 
rested by  this  circumstance,  even  should  all  other  substances  be 
presented  in  abundance. 

It  is  not  mere  accident  that  we  find  on  soils  of  gneiss,  mica- 
slate,  and  granite  in  Bavaria,  of  clinkstone  on  the  Rhone,  of 
basalt  in  the  Vogelsberg,  and  of  clay-slate  on  the  Rhine  and  in 
the  Eifel,  the  finest  forests  of  oaks,  which  cannot  be  produced  on 
the  sandy  or  calcareous  soils  upon  which  firs  and  pines  thrive. 
It  is  explained  by  the  fact  that  trees,  the  leaves  of  which  are  re- 
newed annually,  require  for  their  leaves  six  to  ten  times  more 
alkalies  than  the  fir-tree  or  pine,  and  hence  they  do  not  attain 
maturity  when  placed  in  soils  containing  very  small  quantities 
of  alkalies.*  When  we  see  oaks  growing  on  a  sandy  or  calca- 
reous soil — or  the  red-beech,  the  service-tree,  and  the  wild-cherry, 
for  example — thriving  luxuriantly  on  limestone,  we  may  be  as- 
sured that  alkalies  are  j)resent  in  the  soil,  for  they  are  necessary 
to  their  existence.  Can  we,  then,  regard  it  as  remarkable,  that 
oak  copse  should  thrive  in  America,  on  those  spots  on  which 
forests  of  pines  which  have  grown  and  collected  alkalies  for  cen- 
turies, have  been  burnt,  and  to  which  the  alkalies  are  thus  at 
once  restored  ;  or  that  the  Spariium  scoparium,  Erysimum  latifo- 
Jium,  Blitum  capitatum,  Senecio  viscosus,  plants  remarkable  for 
the  quantity  of  alkalies  contained  in  their  ashes,  should  grow 
with  the  greatest  luxuriance  on  the  localities  of  conflagrations  ?f 


*  One  thf^  \sand  parts  of  the  dry  leaves  of  oaks  yielded  55  parts  of  ashes, 
of  which  9^  parts  consisted  of  alkalies  soluble  in  water  ;  the  same  quantity 
of  pine  lea'  es  gave  only  29  parts  of  ashes,  which  contain  4'G  parts  of  solu- 
ble salts.     (De  Saussure.) 

t  After  the  great  fire  in  London,  large  quantities  of  the  Erysimum  fati- 
folium,  were  observed  growing  on  the  spots  where  a  fire  had  taken  place. 
On  a  similar  occasion  the  Blitum  capitatum  was  seen  at  Copenhagen,  the 
Senecio  viscosus  in  Nassau,  and  the  Spartiitm  scoparium  in  Languedoc. 


lt«  THE  ART  OF  CULTURE. 

All  plants  of  the  grass  kind  require  silicate  of  potash.  Now 
this  is  conveyed  to  the  .soil,  or  rendered  soluble  in  it  by  the  irri- 
gallon  of  meadows.  The  equisetacea,  the  reeds  and  species  of 
cane  containing  such  large  quantities  of  siliceous  earth,  or  sili- 
cate of  potash,  thrive  luxuriantly  in  marshes,  in  argillaceous 
soils  rich  in  potash,  and  in  ditches,  streamlets,  where  the  change 
of  water  renews  constantly  the  supply  of  dissolved  silica.  The 
amount  of  silicate  of  potash  removed  from  a  meadow  in  the  form 
of  hay  is  very  considerable.  We  need  only  call  to  mind  the 
melted  vitreous  mass  found  on  a  meadow  between  Manheim  and 
Heidelberg  after  a  thunder-storm.  This  mass  was  at  first  sup- 
posed to  be  a  meteor,  but  was  found  on  examination  (by  Gmelin) 
to  consist  of  silicate  of  potash ;  a  flash  of  lightning  had  struck  a 
stack  of  hay,  and  nothing  was  founa  in  its  place  except  the  melted 
ashes  of  the  hay. 

Alkalies  and  alkaline  earths  are  not,  however,  the  only  sub- 
stances necessary  for  the  existence  of  most  plants ;  but  other 
substances  besides  alkalies  are  required  to  sustain  the  life  of  plants. 

Phosphoric  acid  has  been  found  in  the  ashes  of  all  plants  hither- 
to examined,  and  always  in  combination  with  alkalies  or  alka- 
line earths.  By  incinerating  the  seeds  of  wheat,  rye,  maize,  peas, 
beans,  and  lentils,  ashes  are  obtained  quite  free  from  carbonic 
acid,  and  consisting  entirely  of  phosphates,  with  the  exception  of 
very  small  quantities  of  sulphates  and  of  chlorides. 

Plants  obtain  their  phosphoric  acid  from  the  soil.  It  is  a  con- 
stituent of  all  land  capable  of  cultivation,  and  even  the  soil  of 
the  heath  at  Liineburg  contains  it  in  appreciable  quantity.  Phos- 
phoric acid  has  been  detected  also  in  all  mineral  waters  in  which 
its  presence  has  been  tested  ;  and  in  those  in  which  it  has  not 
been  found  it  has  not  been  sought  for.  The  most  superficial 
strata  of  the  deposits  of  sulphuret  of  lead  {galena)  contain  crys- 
tallized  phosphate  of  lead  (green  lead  ore) ;  clay  slate,  which 
forms  extensive  strata,  is  covered  in  many  places  with  crystals 
of  phosphate  of  alumina  (Wavellite)  ;  all  its  fractured  surfaces 
are  overlaid  with  this  mineral. 

Apatite  (phosphate  of  lime  of  similar  composition  to  bone  earth) 

After  the  burnings  of  forests  of  pines  in  North  America  poplars  grew  on 
the  same  soil 


FERTILITY  OF  SOILS.  117 

is  found  in  every  fertile  soil.  This  mineral  may  be  easily  recog- 
nised,  in  its  crystalline  form,  in  many  varieties  of  rocks.  It 
occurs  in  this  state  in  the  plutonic,  volcanic,  and  metamorphic 
rocks,  although  it  is  usually  found  only  in  small  quantity.  In 
the  plutonic  and  volcanic  rocks  it  is  found  in  granite  (as  in  the 
mines  of  Johann  Georgenstadt,  Schneeberg,  and  in  the  loose 
gravel  near  Berlin) ;  in  syenite  it  occurs  in  small  crystals,  as  at 
Meissen,  and  in  larger  crystals  at  Friedrichswern,  in  South  Nor- 
way. It  exists  also  in  hypersthene,  as  at  Elfdalen,  in  Sweden, 
and  very  often  in  large  quantity,  as  at  Meiches,  in  the  Vogels- 
berge  (a  district  celebrated  for  its  fertility  in  wheat),  and  also  in 
the  hills  of  Lobau,  in  Saxony ;  Tuhlowitz,  in  Bohemia,  &c. 
It  is  found  in  basalt  and  other  volcanic  rocks  in  various  localities  ; 
for  example,  at  Wickenstein,  at  Hamberg,  and  also  at  Cabo  de 
Gata,  in  Spain,  and  in  the  volcanic  boulders  of  the  Laacher  See. 
Apatite  is  found  also  in  the  metamorphic  rocks,  and  particularly 
in  the  talc  and  chloritic  schists  ;  it  occurs  in  large  yellow  crys- 
tals in  the  micaceous  schists  of  Snarum,  in  Norway  ;  and  in  the 
calcareous  deposits  of  Pargas,  in  Finland,  and  in  the  Lake  Baikal ; 
in  the  deposits  of  magnetic  iron  ore  in  Arendal,  and  in  other 
places  in  Sweden  and  in  Norway.  It  is  found  also  in  the 
oceanic  rocks,  particularly  as  round  fragments  and  grains  in  the 
chalk  of  Cape  la  Heve,  at  Havre,  and  of  the  Capes  Blancnez  and 
Grisnez,  at  Calais,  and  in  the  layers  of  limestone  at  Amberg, 
&c.     (GusTAvus  Rose.) 

The  water  of  the  imperial  spring  at  Aix  la  Chapelle  contains, 
according  to  Monheim,  0*142  grains  of  phosphate  of  soda  in  1  lb. ; 
that  of  the  Quirinus  Spring  contains  the  same  quantity,  and  the 
water  of  the  Rose  spring  contains  0*133  of  the  same  salt.  The 
water  of  the  fountain  of  Carlsbad  contains  0*0016  grains  of  phos- 
phate of  lime.  (Berzelius.)  The  Ferdinand's  spring  contains 
0*010  phosphate  of  soda,  according  to  Wolf.  The  saline  springs 
of  Pyrmont  contain  0*022  phosphate  of  potash,  0*075  phosphate 
of  lime,  and  0*1249  grains  phosphate  of  alumina.  (Krueger.) 
When  we  consider  that  sea-water  contains  phosphate  of  lime  in 
such  small  quantity  that  its  amount  cannot  be  determined  in  a 
pound  of  water,  and  yet  from  this  quantity  all  the  living  animah 
in  the  sea  receive  the  phosphates  contained  in  their  bones  and  fleshj 


^18  THE  ART  OF  CULTURE. 

we  must  admit  that  the  amount  of  phosphates  in  the  above  men- 
tioned mineral  waters  is  very  considerable.  It  may  be  shown 
by  calculation  that  the  water  of  the  fountain  at  Carlsbsui 
must  take  up  many  thousand  pounds  of  phosphate  of  lime  in  its 
passage  through  the  layers  of  rocks. 

A  few  very  simple  experiments  point  out  the  manner  in  which 
the  earthy  phosphates,  and  particularly  phosphate  of  lime,  are 
taken  up  by  the  roots  of  plants. 

Phosphate  of  lime  is  insoluble  in  pure  water,  but  it  dissolves 
readily  in  water  containing  common  salt,  or  a  salt  of  ammonia  ; 
and  in  water  containing  sulphate  of  ammonia  it  dissolves  as 
readily  as  gypsum.  Phosphate  of  lime  is  also  soluble  in  water 
containing  carbonic  acid ;  in  this  respect  it  is  analogous  to  car- 
bonate of  lime. 

The  soil  in  which  plants  grow  furnishes  their  seeds,  roots,  and 
leaves,  with  phosphoric  acid,  and  they  in  turn  yield  it  'to 
animals,  to  be  used  in  the  formation  of  their  bones,  and  of  those 
constituents  of  the  brain  which  contain  phosphorus.  We  may 
form  an  idea  of  the  quantity  of  phosphate  of  magnesia  contained 
in  grain,  when  we  consider  that  the  concretions  in  the  caecum 
of  horses  consist  of  phosphate  of  magnesia  and  ammonia,  which 
must  have  been  obtained  from  the  hay  and  oats  consumed  as 
food.  Twenty-nine  of  these  stones  were  taken  after  death  from 
the  rectum  of  a  horse  belonging  to  a  miller,  in  Eberstadt,  the 
total  weight  of  which  amounted  to  3  lbs.  ;  and  Dr.  F.  Simon  has 
lately  described  a  similar  concretion  found  in  the  horse  of  a 
carrier,  which  weighed  1^  lbs. 

Some  plants  extract  other  matters  from  the  soil  besides 
silica,  the  alkalies,  alkaline  earths,  sulphuric  and  phosphoric 
acids,  which  are  essential  constituents  of  the  plants  ordinarily 
cultivated.  These  other  matters,  we  must  suppose,  supply,  in 
part  at  least,  the  place,  and  perform  the  functions,  of  the  sub- 
stances just  named.  We  may  thus  regard  common  salt,  nitre, 
chloride  of  potassium,  and  other  matters,  as  necessary  constitu- 
ents of  several  plants. 

Clay-slate  contains  generally  small  quantities  of  oxide  of 
copper ;  and  soils  formed  from  micaceous  schist  contain  some 
metallic  fluorides.     Now^   small  quantities  of  these  substances 


FERTILITY  OF  SOILS.  119 

also  are  absorbed  into  plants,  although  we  cannot  affirm  that  they 
are  necessary  to  them. 

It  appears  that  in  certain  cases  fluoride  of  calcium  may  take 
the  place  of  the  phosphate  of  lime  in  the  bones  and  teeth ;  at 
least  it  is  impossible  otherwise  to  explain  its  constant  presence  in 
the  bones  of  antediluvian  animals,  by  which  they  are  distin- 
guished from  those  of  a  later  period.  The  bones  of  human 
skulls  found  at  Pompeii  contain  as  much  fluoric  acid  as  those  of 
animals  of  a  former  world  ;  for  if  they  be  placed  in  a  state  of 
powder  in  glass  vessels,  and  digested  with  sulphuric  acid,  the  in- 
terior of  the  vessel  will,  after  twenty-four  hours,  be  found 
powerfully  corroded  (Liebig)  ;  whilst  the  bones  and  teeth  of 
animals  of  the  present  day   contain  only  traces  of  it.     (Ber- 

ZELIUS.)* 

In  spring  and  in  the  first  half  of  the  summer,  when  the 
earth  is  still  moist  with  water,  it  is  quite  certain  that  a  greater 
quantity  of  alkaline  bases  and  of  salts  must  enter  the  organism 
of  a  plant,  than  in  the  height  of  summer,  when  there  is  a 
deficiency  of  water,  this  being  the  means  of  carrying  the  bases 
to  the  plant. 

In  many  districts  the  crops  of  corn  for  the  whole  year  depend 
upon  a  single  shower  of  rain  ;  for  when  water  is  deficient  at  a 
certain  period  of  the  growth  of  plants,  their  future  progress  is- 
retarded.  The  introduction  of  water  to  a  soil  is,  properly  speak- 
ing, an  introduction  of  alkalies  and  of  certain  salts,  which,  by 
means  of  rain-water,  become  fit  to  be  absorbed  by  plants.  In 
the  middle  of  summer  the  air  is  much  more  charged  with  the 
vapor  of  water  than  at  other  seasons  of  the  year,  and,  therefore, 

*  The  researches  of  Daubeny,  however,  tend  to  show,  not  only  that  the 
amount  of  fluoride  of  calcium  in  bones  is  larger  than  is  commonly  sup- 
posed, reaching  in  some  cases  to  10  or  12  per  cent,  of  the  bone  earth,  but 
that  recent  bones  contain  as  much  as  fossil  and  ancient  bones  do.  In 
recent  bones,  however,  it  cannot  be  so  easily  detected,  until  they  have 
been  burned,  the  presence  of  gelatine  seeming  to  impede  the  detection  of 
fluorine  by  the  usual  tests.  Dr.  G.  Wilson  has  very  recently  shown  that 
fluoride  of  calcium  is  soluble  in  water  to  an  extent  quite  sufficient  to  ac- 
count for  its  very  general  diffusion.  He  has  found  it  in  sea- water,  and  in 
all  the  springs  which  he  has  examined.  Ihiubeny  suggests  that  the  pre- 
sence of  fluoride  of  calcium  in  bones  may  prevent  any  tendency  to  crystal- 
lization,  and  thus  confer  on  the  bone  additional  toughness, — W,  G. 


120  THE  ART  OF  CULTURE. 

the  hydrogen  which  is  essential  to  the  nouriphment  of  plants,  if 
presented  to  them  in  sufficient  quantity. 

When  the  soil  is  deficient  in  moisture,  we  observe  a  phenome- 
non, which  appeared  quite  inexplicable,  before  we  understood 
the  importance  of  mineral  matters,  as  means  of  nourishment  to 
plants.  We  see  the  leaves  close  to  the  soil  (those  which  had 
been  first  developed)  lose  their  vitality,  shrink  and  fall  off, 
after  becoming  yellow,  without  the  apparent  action  of  any  inju- 
rious cause.  This  phenomenon  is  not  perceived,  in  this  form,  in 
moist  years,  nor  is  it  observed  with  evergreens,  and  only  rarely 
with  those  plants  which  throw  out  long  deep  roots ;  it  is  observed 
only  in  harvest  and  in  winter  with  perennial  plants. 

The  cause  of  this  phenomenon  is  now  quite  apparent.  The 
matured  leaves  absorb  continually  from  the  air  carbonic  acid 
and  ammonia,  which  are  converted  into  the  constituents  of  new 
leaves,  buds,  and  twigs  ;  but  this  conversion  cannot  be  effected 
without  the  co-operation  of  alkalies  and  of  other  inorganic  sub- 
stances. When  the  soil  is  moist, these  are  constantly  conveyed 
to  the  plants,  which  retain  their  green  color  in  consequence. 
But  in  dry  weather,  the  deficiency  of  water  prevents  them  being 
absorbed  by  the  plant;  and  in  consequence  of  this,  they  are 
taken  from  the  plant  itself.  The  mineral  ingredients  in  the  juice 
of  the  fully  formed  leaves  are  abstracted  from  them,  and  are 
employed  in  the  formation  of  the  young  sprout ;  and  when  the 
seeds  become  developed  the  vitality  of  the  old  leaf  is  completely 
destroyed.  These  withered  leaves  contain  mere  traces  of  soluble 
salts,  while  the  buds  and  sprouts  are  remarkably  rich  in  these 
ingredients. 

The  reverse  of  this  phenomenon  is  seen  in  the  case  of  many 
kitchen  plants,  when  they  are  supplied  with  rich  manure  con- 
taining an  excess  of  mineral  ingredients ;  salts  are  separated 
from  the  surface  of  their  leaves,  and  cover  them  with  a  thin 
white  crust.  In  consequence  of  these  exudations  the  plant  be- 
comes sickly,  the  organic  activity  of  the  leaves  diminishes,  the 
growth  of  the  plant  is  destroyed,  and  if  this  condition  lasts,  the 
plant  finally  dies.  These  observations  are  best  made  on  plants 
with  leaves  of  large  dimensions,  through  which  large  quantities 
of  water  are  evaporated. 


FERTILITY  OF  SOILS.  12\ 

This  disease  generally^  attacks  turnips,  gourds,  and  peas, 
when  the  soil  is  drenched  with  sudden  and  violent  rain,  after 
continued  dry  weather,  at  the  time  when  the  plants  are  near,  but 
have  not  attained  maturity  ;  it  is  also  necessary  for  its  occur- 
rence, that  dry  weather  should  again  happen  after  the  rain. 

By  the  rapid  evaporation  of  the  water  absorbed  by  the  roots, 
a  laiger  quantity  of  salts  enters  the  plants  than  they  are  able  to 
use.  The  salts  effloresce  on  the  surface  of  the  leaves,  and 
when  they  are  juicy,  act  as  if  the  plants  had  been  treated  with 
solutions  of  salts,  in  greater  quantity  than  their  organism  could 
bear.  Of  two  plants  of  the  same  kind  the  one  nearest  maturity 
is  most  liable  to  this  disease ;  if  the  other  plant  has  either  been 
planted  at  a  later  period,  or  if  its  development  has  been  restrain- 
ed, the  causes,  which  exercised  injurious  effects  upon  the  first 
plant,  accelerate  the  development  of  the  latter.  The  germ 
springing  out  of  the  earth,  the  leaf  on  coming  out  of  the  bud,  the 
young  stem,  and  the  green  sprouts,  contain  a  much  larger  quan- 
tity of  salts  with  alkaline  bases  and  give  ashes  on  incineration 
much  richer  in  alkaline  ingredients,  than  parts  of  the  matured 
plant.  The  leaves,  being  the  part  in  which  the  absorption  and 
decomposition  of  carbonic  acid  is  effected,  are  much  richer  in 
mineral  ingredients  than  other  parts  of  the  plant. 

The  simple  fact  that  a  plant  is  restrained  in  growth  by  the 
want  of  rain  to  convey  to  it  alkalies,  proves  completely  that  these 
alkalies  play  a  most  important  part  in  vegetation. 

Although  it  was  found  by  Saussure  that  wheat  before  blossom- 
ing yielded  -j^-^,  in  blossom  j^-^-ff,  and  after  the  ripening  of  the 
seeds  only  half  this  quantity  of  ashes  ;  it  cannot  hence  be  con- 
cluded that  the  ingredients  of  the  soil  present  in  the  young  and 
growing  plants,  were  again  returned  to  the  soil.  Equal  quanti- 
ties of  young  plants  yield  twice  the  amount  of  ashes  that  matured 
plants  do  ;  but  this  evidently  arises  from  the  circumstance,  that 
new  quantities  of  organic  constituents  are  added  to  the  carbon, 
hydrogen,  and  nitrogen,  previously  existing  in  the  young  plant. 
The  amount  of  ashes  remains  the  same  in  both  plants,  although 
their  relative  proportions  have  become  different. 

We  may  feel  assured  that  the  alkalies  contained  in  the  vine, 
in  the  potatoe,  and  beet,  and  found  in  the  juices,  united  with  tar- 
7 


122  THE  ART  OF  CULTURE. 

taric,  citric,  oxalic,  and  malic  acids,  are  not  merely  present  for 
the  purpose  of  being  used  in  druggists*  shops,  or  in  our  house^ 
hold,  as  acid  or  as  neutral  salts.  These  organic  acids  must  be 
necessary  for  the  formation  of  certain  constituents  in  the  plants. 

We  have  already  come  to  the  conclusion,  that  the  carbon  of 
all  plants  is  derived  from  carbonic  acid  ;  tartaric,  oxalic,  citric 
acid,  (kc,  must,  therefore,  obtain  their  carbon  from  the  same 
source.  But,  can  we  conceive  that  the  carbon  forms  a  direct 
and  immediate  combination  with  hydrogen  for  the  production  of 
substances  so  various  as  sugar,  starch,  woody  fibre,  resin,  wax, 
and  oil  of  turpentine  ?  Is  it  not  much  more  probable  that  the 
conversion  of  the  carbon  of  carbonic  acid  into  the  constituent  of 
a  plant  proceeds  in  a  gradual  manner ;  that  by  the  union  of  the 
constituents  of  water  with  carbonic  acid,  a  substance  is  formed, 
becoming  gradually  poorer  in  oxygen  ;  and  that  the  carbon  as-, 
sumes  the  form  of  oxalic,  tartaric,  or  other  organic  acids,  before 
it  is  converted  into  sugar,  starch,  or  woody  fibre  ? 

According  to  this  view,  a  ready  and  simple  explanation  is  fur- 
nished of  the  necessity  of  alkalic  bases  to  vegetable  life  ;  for 
they  are  present  for  the  purpose  of  effecting  the  conversion  of 
carbonic  acid  into  a  living  part  of  a  plant.  The  smallest  parti- 
cles of  sugar,  or  of  organic  acids,  when  separated  from  plants, 
follow  their  own  peculiar  attractions  ;  they  form  crystals,  or  they 
follow  the  power  which  induces  the  cohesion  of  their  atoms,  but 
still  their  carbon  is  capable  of  being  converted  into  a  constituent 
of  a  living  organ  ;  and,  although  sugar  and  tartaric  acid  have 
been  formed  by  vital  agencies,  they  do  not  in  themselves  possess 
any  vital  functions. 

From  the  preceding  part  of  this  chapter  it  will  be  seen  that 
fallow  is  that  period  of  culture  when  the  land  is  exposed  to  pro- 
gressive disintegration  by  the  action  of  the  weather,  for  the  pur- 
pose of  liberating  a  certain  quantity  of  alkalies  and  silica  to  be 
absorbed  by  future  plants. 

The  careful  and  frequent  working  of  fallow  land  will  accele- 
rate and  increase  its  disintegration  ;  for  the  purposes  of  culture  it 
is  quite  the  same  whether  the  land  be  covered  with  weeds,  or 
with  a  plant  which  does  not  extract  the  potash  of  the  soil. 


SCIENCE  AND  PRACTICE.  123 


CHAPTER   X. 

On  Fallow. 

Agriculture  is  both  an  art  and  a  science.  Its  scientific  basit 
embraces  a  knowledge  of  all  the  conditions  of  vegetable  life,  of 
the  origin  of  the  elements  of  plants,  and  of  the  sources  whence 
they  derive  their  nourishment. 

From  this  knowledge  fixed  rules  are  formed  for  the  practice 
of  the  art,  that  is,  for  the  necessity  or  advantage  of  all  the 
mechanical  operations  of  the  farm,  by  which  the  land  is  prepared 
for  the  growth  of  plants,  and  by  which  those  causes  are  removed,- 
which  might  exercise  an  injurious  influence  upon  them. 

Experience  acquired  in  the  practice  of  this  art  can  never  stand 
in  contradiction  to  its  scientific  principles  ;  because  the  latter 
have  been  deduced  from  all  the  observations  of  experience,  and 
are  actually  an  intellectual  expression  of  it.  Neither  can  The- 
ory ever  stand  in  antagonism  to  Practice,  for  it  is  merely  the 
tracing  back  of  a  class  of  phenomena  to  their  ultimate  causes. 

A  field  upon  which  we  cultivate  the  same  plants  successively 
for  a  number  of  years,  may  become  unfertile  for  these  plants  in 
three  years  ;  whilst  another  field  may  last  seven,  another  twenty, 
and  another  one  hundred  years,  without  losing  its  fertility.  One 
field  bears  wheat  but  not  beans ;  another  bears  turnips  but  not 
tobacco  ;  and  a  third  yields  rich  crops  of  turnips,  biit  does  not 
bear  clover. 

What  is  the  reason  that  a  field  loses  gradually  its  fertility  for 
the  same  plant  ?  What  is  the  reason  that  a  certain  kind  of  plant 
flourishes  on  it,  and  that  another  fails  ? 

These  questions  are  proposed  by  the  Science  of  Agri- 
culture. 

What  means  are  necessary  to  enable  a  field  to  sustain  its  fer- 


124  ON  FALLOW. 


tility  for  the  same  plant,  and  to  make  it  fit  for  the  cultivation  of 
one,  two,  or  for  all  plants  ? 

The  latter  questions  are  proposed  by  the  art  of  Agri- 
CTTLTURJS ;  but  they  are  not  susceptible  of  solution  by  means  of 
the  art. 

When  a  farmer  institutes  experiments  for  the  purpose  of  mak- 
ing  a  field  fertile  for  plants  which  it  would  not  formerly  bear, 
the  prospect  of  success  must  be  small,  unless  he  is  guided  by 
scientific  principles.  Thousands  of  farmers  try  analogous  expe- 
riments in  various  ways,  and  the  results  of  these  constitute  a 
mass  of  experience,  out  of  which  a  method  of  culture  is  finally 
formed  ;  and  this  method  suffices  for  a  certain  district.  But  the 
same  method  fails  with  a  neighboring  district,  or  it  may  prove 
actually  injurious. 

What  an  immense  amount  of  capital  and  power  is  lost  in  such 
experiments  as  these  !  What  a  very  different  and  much  more 
certain  path  does  Science  follow  I  It  does  not  put  us  in  danger 
of  failure,  and  it  gives  us  the  best  security  of  success. 

If  the  causes  of  failure  or  the  causes  of  sterility  of  a  soil  for 
one,  two,  or  three  plants  be  ascertained,  the  means  of  obviating 
the  sterility  follow  as  a  matter  of  course. 

The  methods  of  cultivating  soils  vary  with  their  geological 
characters.  In  basalt,  grauwacke,  porphyry,  sandstone,  lime- 
stone, &c.,  let  us  suppose  that  there  are  present,  in  different 
proportions,  certain  chemical  compounds  essential  to  the  growth 
of  plants,  and  which  must  therefore  exist  in  fertile  soils;  then 
we  are  able  to  explain  in  a  very  simple  manner  the  diflTerence 
in  the  methods  of  culture  ;  for  it  is  obvious  that  the  soils  formed 
by  the  disintegration  of  the  above  rocks  must  vary  in  the  pro- 
portion of  their  essential  constituents,  just  as  the  rocks  themselves 
vary. 

Wheat,  clover,  and  turnips,  require  certain  constituents  from 
the  soil  ;  and  hence  they  cannot  flourish  in  a  soil  from  which 
these  are  absent.  Science  enables  us  to  recognise  these  neces- 
sary constituents,  by  the  analysis  of  the  ashes  of  the  plants  ;  and 
if  we  discover  the  absence  of  these  ingredients  from  the  soil,  the 
cause  of  its  sterility  is  obvious. 


WEATHERING  OF  ORES.  125 

The  means  of  obviating  this  sterility  follows  from  a  knowledge 
of  its  cause. 

Empiricism  ascribes  all  results  to  the  art,  that  is,  to  the  me- 
chanical  operations  employed  in  cultivation,  without  inquiring 
the  causes  upon  which  their  use  depends.  But  a  knowledge  of 
these  causes  is  of  the  highest  importance  ;  for  such  knowledge 
would  prevent  the  lavish  expenditure  of  capital  and  of  power, 
and  would  enable  us  to  use  them  in  the  most  advantageous  man- 
ner. Is  it  conceivable  that  the  entrance  of  the  ploughshare  or 
of  the  harrow  into  the  earth — that  the  contact  of  iron  with  the 
soil — can  act  as  a  charm  to  impart  fertility  ?  No  one  can  enter- 
tain such  an  opinion  ;  and  yet  the  causes  of  their  action  have  not 
yet  been  inquired  into,  and  much  less  have  they  been  explained. 
It  is  quite  certain  that  it  is  the  great  mechanical  division,  the 
change  and  increase  of  surface,  obtained  by  the  careful  plough- 
ing and  breaking  up  of  the  soil,  which  exercises  so  very  favora- 
ble an  influence  on  its  fertility  ;  but  these  mechanical  operations 
are  only  the  means  to  attain  that  end. 

Among  the  effects  produced  by  time,  particularly  in  the  case 
of  fallow,  or  that  period  during  which  a  field  remains  at  rest, 
science  recognises  certain  chemical  actions,  which  proceed  unin- 
terruptedly by  means  of  the  influence  exercised  by  the  constitu- 
ents of  the  atmosphere  upon  the  surface  of  the  solid  crust  of  the 
earth.  By  the  action  of  the  carbonic  acid  and  oxygen  in  the  air, 
aided  by  moisture  and  by  rain-water,  the  power  of  dissolving  in 
water  is  given  to  certain  constituents  of  rocks,  or  of  their  debris, 
from  which  arable  land  is  formed  ;  these  ingredients,  in  con- 
sequence of  their  solubility,  become  separated  from  the  insoluble 
constituents. 

These  chemical  actions  serve  to  explain  the  effects  produced 
by  the  hand  of  time,  which  destroys  human  structures,  and  con- 
verts gradually  the  hardest  rocks  into  dust.  It  is  by  their  influ- 
ence that  certain  ingredients  of  arable  land  become  fit  for  assimi- 
lation by  plants ;  and  the  object  of  the  mechanical  operations  of 
the  farm  is  to  obtain  this  result.  Their  action  consists  in  acce- 
lerating the  weathering  or  disintegration  of  the  soil,  and  thus 
offers  to  a  new  generation  of  plants  their  necessary  mineral  con- 
stituents, in  a  form  fit  for  reception.     The  celerity  of  the  disin- 


.125  ON  FALLOW. 


tegration  of  a  solid  body  must  be  in  proportion  to  its  surface ; 
for  the  more  points  which  we  expose  to  the  action  of  the  destruc 
tive  agencies,  the  more  rapidly  will  their  effects  be  produced. 

When  a  chemist  subjects  a  mineral  to  analysis,  in  order  to 
break  up  the  compound,  that  is,  to  give  solubility  to  its  constitu- 
ents, he  is  obliged  to  perform  the  very  tedious  and  difficult  task 
of  reducing  it  to  an  impalpable  powder.  He  separates  the  fine 
dust  from  the  grosser  particles  by  means  of  a  fine  sieve,  or  by 
elutrialion,  and  exerts  his  utmost  patience  to  obtain  a  fine  pow- 
der ;  because  he  is  aware  that  the  solution  of  the  mineral  will 
be  incomplete,  and  that  all  his  operations  will  prove  ineffectual, 
if  he  be  at  all  careless  in  this  preliminary  operation. 

The  influence  of  an  increased  surface  upon  the  weathering  of 
a  stone,  or,  in  other  words,  on  the  changes  which  it  suffers  by  the 
action  of  the  constituents  of  the  atmosphere,  and  by  water,  is 
very  well  pointed  out  in  the  interesting  description  given  by  Dar- 
win of  the  gold  mines  at  Yaquil,  in  Chili.  The  gold  ores,  after 
being  reduced  to  a  very  fine  powder  in  mills,  are  subjected  to  a 
process  by  which  the  particles  of  metal  are  separated  from  the 
lighter  parts  of  the  ore.  The  particles  of  stone  are  carried  away 
by  a  stream  of  water  ;  while  those  of  gold  fall  to  the  bottom. 
The  former  are  conducted  into  a  tank,  where  they  are  permitted 
to  deposit.  As  the  tank  fills  gradually,  the  fine  mud  is  removed 
from  it,  and  is  left  in  heaps  to  itself,  that  is,  it  is  exposed  to  the 
action  of  the  air  and  of  moisture.  From  the  nature  of  the  elutria- 
tion  to  which  it  was  subjected,  the  finely-divided  ore  can  no  longer 
contain  any  salts,  or  soluble  ingredients.  Whilst  it  lay  at  the 
bottom  of  the  tank  covered  with  water,  and  therefore  excluded 
from  air,  it  suffered  no  change  ;  but  when  exposed  to  air,  a  pow- 
erful chemical  action  ensues  in  the  heaps,  and  this  action  is 
recognised  by  the  abundant  efflorescence  of  salts,  which  cover 
their  surface,  from  the  effects  of  disintegration.  After  the  finely 
divided  ore  has  be^n  exposed  to  the  action  of  the  weather  for  two 
or  three  years,  during  which  time  it  hardens,  it  is  again  elutri- 
ated, and  the  processes  of  exposure  and  elutriation  are  repeated 
six  or  seven  times,  new  quantities  of  gold  being  obtained  each 
time,  although  in  smaller  proportions ;  this  gold  is  liberated  by 
the  chemical  process  of  weathering  or  of  disintegration. 


ACTION  OF  LIME.  121 


The  same  chemical  actions  as  those  now  described  proceed  in 
our  arable  land,  and  it  is  to  accelerate  and  increase  these  that  we 
employ  the  mechanical  operations  of  culture.  We  renew  the 
surface  of  the  soil,  and  endeavor  to  make  every  particle  of  it 
accessible  to  the  action  of  carbonic  acid  and  of  oxygen.  Thus 
we  procure  a  new  provision  of  soluble  mineral  substances,  which 
are  indispensable  for  the  nourishment  and  luxuriance  of  a  new 
generation  of  plants. 

All  cultivated  plants  require  alkalies  and  alkaline  earths, 
although  each  of  them  may  use  different  proportions  of  the  one 
or  of  the  other ;  the  cereals  do  not  flourish  in  a  soil  deficient  in 
silica  in  a  soluble  state. 

Silicates,  as  they  occur  in  nature,  differ  very  materially  in 
their  tendency  to  suffer  disintegration,  and  in  the  resistance 
which  they  offer  to  the  action  of  atmospheric  agents.  The 
granite  of  Corsica  and  the  felspar  of  Carlsbad  crumble  into  dust 
in  a  space  of  time  during  which  the  polished  granite  of  the  Berg- 
strasse  does  not  even  lose  its  lustre. 

There  are  certain  kinds  of  soil  so  rich  in  silicates  prone  to 
disintegration,  that  every  year,  or  every  two  years,  a  quantity  of 
silicate  of  potash  is  rendered  fit  for  assimilation  sufficient  for  the 
formation  of  the  leaves  and  stems  of  a  whole  crop  of  wheat.  In 
Hungary  there  are  large  districts  of  land,  on  which,  since  the 
memory  of  man,  corn  and  tobacco  have  been  cultivated  in  alter- 
nate years,  without  the  restoration  of  the  mineral  ingredients 
carried  away  in  the  corn  and  in  the  straw.  There  are  other 
fields,  on  the  contrary,  which  do  not  yield  sufficient  silicate  of 
potash  until  after  two,  thrt-^,  or  more  years. 

Fallow,  in  its  most  extended  sense,  means  that  period  of  cul- 
ture during  which  a  soil  is  exposed  to  the  action  of  the  weather, 
for  the  purpose  of  enriching  it  in  certain  soluble  ingredients.  In 
a  more  confined  sense,  the  time  of  fallow  may  be  limited  to  the 
interval  inthe  cultivation  of  cereal  plants  ;  for  a  magazine  of 
soluble  silicates  and  of  alkalies  is  an  essential  condition  to  the 
existence  of  such  plants.  The  cultivation  of  potatoes  or  of  tur- 
nips during  the  interval  will  not  impair  the  fertility  of  the  field 
for  the  cereals  which  are  to  succeed  (supposing  the  supply  of 


138  ON  FALLOW. 


alkalies  to  be  sufficient  for  both),  because  the  former  plants  do  not 
require  any  of  the  silica  necessary  for  the  latter. 

It  follows  from  the  preceding  observations,  that  the  mechanical 
operations  in  the  field  are  the  simplest  and  most  economical  means 
of  rendering  accessible  to  plants  the  nutritious  matters  in  the  soil. 

But,  it  may  be  asked,  are  there  no  other  means  besides  the 
mere  mechanical  operations,  of  liberating  the  ingredients  of  a 
soil,  and  of  fitting  them  for  reception  by  the  organism  of  plants  ? 
There  are  such  means,  and  one  of  the  most  simple  and  efficacious 
of  them  is  the  practice  employed  in  England  for  the  last  century, 
of  manuring  soils  with  burnt  lime. 

In  order  to  form  a  proper  conception  of  the  action  of  lime  on 
soils,  we  must  remember  the  processes  employed  by  chemists 
to  effect  the  speedy  decomposition  of  a  mineral,  and  to  render 
soluble  its  ingredients.  In  order  to  dissolve  finely-pulverized 
felspar  in  an  acid,  it  would  be  necessary  to  expose  it  to  continued 
digestion  for  weeks,  or  even  for  months.  But  when  the  felspar 
is  mixed  with  lime,  and  is  exposed  to  a  moderately  strong  heat, 
the  lime  enters  into  chemical  combination  with  the  constituents 
of  the  felspar.  A  part  of  the  alkali  (potash)  imprisoned  in  the 
felspar  is  now  set  at  liberty,  and  a  simple  treatment  of  the  felspar 
with  acid,  in  the  cold,  now  suffices  to  dissolve  the  lime  and  the 
other  constituents  of  the  mineral.  The  silica  is  dissolved  by  the 
acid  to  such  an  extent,  that  the  whole  assumes  the  consistence  Oi 
a  transparent  jelly. 

Most  of  the  silicates  of  alumina  and  alkalies,  when  mixed 
with  slacked  lime  and  kept  in  continued  contact  in  a  moist  state, 
behave  in  a  similar  manner  to  felspar  when  heated  with  lime. 
When  a  mixture  of  common  clay,  or  of  pipe-clay,  and  water,  is 
added  to  milk  of  lime,  the  whole  becomes  immediately  thicker  on 
agitation.  When  they  are  left  in  contact  for  several  months,  it 
is  found  that  the  mixture  gelatinizes  on  the  addition  of  an  acid — 
a  property  which  the  mixture  of  clay  and  water  did  not  possess, 
or  only  to  a  very  small  degree,  before  the  contact  with  lime. 
The  clay  is  broken  up  by  the  union  of  certain  of  its  constituents 
with  lime ;  and,  what  is  still  more  remarkable,  most  of  the  alka- 
lies contained  in  it  are  set  at  liberty.  These  beautiful  observa- 
tions were  first  made  by  Fuchs  of  Munich  ;  and  they  have  not 


BURNING  OF  LAND.  *79 


only  led  to  conclusions  on  the  nature  and  properties  of  hydraulic 
limestones,  but,  what  is  far  more  important,  they  have  explained 
the  action  of  slacked  lime  upon  soils,  and  they  have  thus  furnish- 
ed an  invaluable  means  of  liberating  from  the  soil  the  alkalies 
which  are  indispensable  to  the  existence  of  plants. 

In  October,  the  fields  in  Yorkshire  and  Lancashire  have  the 
appearance  of  being  covered  with  snow.  The  soil  for  miles  is 
seen  covered  either  with  lime  previously  slacked,  or  with  lime 
that  hfcs  slacked  itself  by  exposure  to  air.  During  the  moist 
months  of  winter,  it  exercises  its  beneficial  influence  on  the  stiff 
clayey  soils. 

According  to  the  old  theory  of  humus,  we  ought  to  suppose 
that  burnt  lime  would  exercise  a  very  injurious  influence  on  soils, 
by  destroying  the  organic  matter  contained  in  them,  and  by  thus 
rendering  them  unfit  to  supply  a  new  vegetation  with  humus. 
But,  on  the  contrary,  it  is  found  that  lime  heightens  the  fertility 
of  a  soil.  The  cereals  require  the  alkalies  and  silicates  liberated 
by  the  lime  and  rendered  fit  for  assimilation  by  plants.  If  there 
be  present  decaying  matter  yielding  to  the  plants  carbonic  acid, 
their  development  may  be  favored  by  this  means  ;  but  this  is 
not  necessary.  For  if  we  furnish  to  the  soil  ammonia,  and  to 
the  cereals  the  phosphates  essential  to  their  growth,  in  the  event 
of  their  being  deficient,  we  furnish  all  the  conditions  necessary 
for  a  rich  crop,  as  the  atmosphere  forms  an  inexhaustible  maga- 
zine of  carbonic  acid. 

In  districts  where  fuel  is  cheap,  an  equally  favorable  influence 
is  exerted  on  clayey  soils  by  the  system  of  burning. 

It  is  not  very  long  since  that  chemists  observed  the  remarka- 
ble changes  which  take  place  in  the  properties  of  clay  when  it  is 
burned  :  these  were  first  studied  in  the  analysis  of  several  sili- 
cates of  alumina.  Many  of  them,  which  are  not  at  all  attacked 
by  acids  in  their  natural  state,  acquire  complete  solubility  when 
they  are  previously  melted  by  heat.  To  this  class  of  silicates 
belong  pipe  and  potter's  clay,  loam,  and  the  different  varieties  of 
clay  occurring  in  soils.  In  the  natural  state  of  clay,  it  may  be 
digested  with  concentrated  sulphuric  acid  for  hours,  without  dis- 
solving in  any  appreciable  quantity  ;  but  when  the  clay  is  slightly 
burnt  (as  is  done,  for  example,  in  several  alum  works)  it  dissolves 


^30  ON  FALLOW. 


in  acids  with  great  ease,  while  the  silica  is  separated  in  its  gela- 
tinous and  soluble  form.  Common  potter's  clay  forms  generally 
very  sterile  soils,  although  it  contains  within  it  all  the  conditionis 
for  the  luxuriant  growth  of  plants  ;  but  the  mere  presence  of 
these  conditions  does  not  suffice  to  render  them  useful  to  vegeta- 
tion. The  soil  must  be  accessible  to  air,  oxygen,  and  carbonic 
acid,  for  these  are  the  principal  conditions  to  favor  the  develop- 
ment of  th6  roots.  Its  constituents  must  be  contained  in  a  state 
fit  to  be  taken  up  by  plants.  Plastic  clay  is  deficient  in  all  these 
properties,  but  they  are  communicated  to  it  by  a  gentle  calcina- 
tion.* 

The  great  difference  between  burnt  and  unburnt  clay  may  be 
observed  in  places  where  burnt  bricks  are  used  for  building. 
In  Flanders,  where  almost  all  the  houses  are  constructed  with 
burnt  bricks,  the  surface  of  the  walls,  after  exposure  for  a  few 
days  to  the  action  of  the  weather,  becomes  covered  with  an  efflo- 
rescence of  salts.  When  these  salts  are  washed  away  by  the 
rain,  a  new  efflorescence  again  appears ;  and  in  some  cases,  as 
the  gateway  of  the  fortress  at  Lille,  this  may  be  observed,  even 
though  the  walls  have  stood  for  centuries.  The  efflorescence 
consists  of  carbonates  and  of  sulphates  with  alkaline  bases — salts 
that  are  known  to  play  a  most  important  part  in  the  economy  of 
vegetation.  Lime  exercises  a  striking  effect  upon  these  saline 
efflorescences,  for  it  may  be  observed,  that  they  first  appear  in 
those  parts  where  the  mortar  and  bricks  come  in  contact. 

It  is  obvious  that  mixtures  of  clay  and  lime  contain  all  the  con- 
ditions necessary  for  the  decomposition  of  the  silicate  of  alumina, 
and  for  rendering  soluble  the  alkaline  silicates.  Lime  dissolved 
in  water  by  means  of  carbonic  acid  acts  upon  clay  in  the  same 
way  that  milk  of  lime  does.  This  fact  explains  the  favorable 
influence  of  marl  upon  most  soils,  marl  being  a  clay  rich  in  lime. 
Indeed  there  are  certain  marly  soils  surpassing  in  fertility,  for  all 
plants,  soils  of  any  other  kind.     Burnt  marl  must  be  in  a  very 

*  The  author  saw  an  example  of  this  in  the  garden  of  Mr.  Baker,  at 
Hardwick  Court,  near  Gloucester.  The  soil  consisted  of  a  stiff  clay,  and, 
from  a  state  of  complete  sterility,  had  bien  made  remarkably  fertile,  by 
simple  burning.  The  operation,  in  this  case,  was  carried  on  to  a  depth  of 
three  feet, — certainly  not  an  econcmical,  although  a  completely  successful 
■experiment. 


PHYSICAL  STATE  OF  SOILS.  131 

superior  state  for  manure  ;  and  this  remark  applies  to  all  sub- 
stances of  a  similar  composition, — to  the  hydraulic  limestones, 
for  example.  By  these  the  plants  are  furnished,  not  only  with 
alkalies,  but  also  with  silica,  in  a  state  fit  for  reception.  Many 
of  the  hydraulic  limestones,  or  the  natural  cements,  as  they  are 
called,  after  being  mixed  in  their  burnt  state  with  water,  yield  to 
it,  in  a  few  hours,  so  much  caustic  alkali,  that  the  water  may  be 
employed  as  a  weak  ley  for  the  purposes  of  washing. 

The  ashes  of  brown  coal  and  of  mineral  coal  are  used  in  many 
'listricts  as  excellent  means  of  improving  certain  soils.  Those 
ashes  are  to  be  preferred  that  gelatinize  on  the  addition  of  an  acid, 
or  that  become  stony  and  hard  after  some  time,  like  hydraulic 
cement,  when  mixed  with  lime  and  water. 

The  mechanical  operations  of  the  farm,  fallow,  the  applications 
of  lime,  and  the  burning  of  clay,  unite  in  elucidating  the  same 
scientific  principle.  They  are  the  means  of  accelerating  the 
disintegration  of  the  alkaline  silicates  of  alumina,  and  of  sup- 
plying to  plants  their  necessary  constituents  at  the  commence- 
ment of  a  new  vegetation. 

It  must  be  distinctly  understood,  that  the  previous  remarks 
apply  only  to  those  fields  which  are  in  a  favorable  mechanical 
state  for  the  development  of  plants ;  for  this,  in  conjunction  with 
the  other  necessary  conditions,  has  the  greatest  influence  on  fer- 
tility. A  stiff,  heavy  clayey  soil  offers  too  much  resistance  to 
the  spreading  out  and  increase  of  the  roots  of  a  quick-growing 
summer  plant.  It  is  obvious  that  such  a  soil  will  be  rendered 
more  accessible  to  the  roots,  as  well  as  to  air  and  moisture,  by  a 
simple  mixture  with  quarz  or  with  sand,  and  this  may  often  prove 
more  effectual  in  improving  it  than  the  most  diligent  ploughing. 
When  we  supply  to  a  soil  easily  penetrable  by  the  roots  of  plants, 
as  well  as  by  air  and  moisture,  in  the  form  of  ashes,  the  consti- 
tuents that  we  re  1  loved  in  the  crops,  the  soil  will  retain  all  its 
original  favorable  physical  state.  In  like  manner,  we  can  restore 
the  original  chemical  composition  to  stiff,  heavy  clay  soils ; 
but  it  is  better  for  such  soils  to  restore  the  necessary  ingredients 

IN    THE  FORM  OF  STABLE  VARD    MANURE,    than    tO  do    SO,  ES    in    the 

former  case,  by  means  of  ashes.  By  the  improvement  of  the 
physical  condition  of  the  soil,  its  fertility  is  increased.  In  this 
respect  excrements  are  of  very  various  values,  although  they  may 


1^^  ...    ON  FALLOW. 


contain  the  same  chemical  constituents;  thus  sheep's  dung  ia 
plose  and  heavy,  while  the  dung  of  cows  and  of  horses,  especially 
when  mixed  with  straw,  is  light  and  pcrous. 

In  hot  summers,  accompanied  by  light  and  partial  showers  of 
rain,  porous  soils  of  no  great  fertility  yield  often  better  crops 
than  richer  stiff  soils.  The  rain  falling  on  the  porous  soil  is  im- 
mediately absorbed  and  reaches  the  roots,  whilst  that  falling  on 
the  heavy  soils  is  evaporated  before  it  is  enabled  to  penetrate 
them. 

A  soil  destitute  of  cohesion,  like  quick-sand,  is  not  fitted  for 
the  cultivation  of  plants  in  general.  Finally,  there  are  certain 
kinds  of  soils  which  ought,  from  their  chemical  composition,  to 
be  very  fertile,  but  which,  on  the  contrary,  are  sterile  for  many 
kinds  of  plants  :  such  soils  are  those  that  consist  of  clay  mixed 
with  a  large  quantity  of  very  fine  sand.  Such  a  soil  converts 
itself  into  a  kind  of  thick  mud  after  a  heavy  fall  of  rain,  and  thus 
prevents  all  access  of  air,  and  it  dries  without  much  contraction. 

If  we  were  to  apply,  in  all  their  extent,  to  porous,  sandy,  or 
calcareous  soils,  or  to  a  soil  of  the  nature  mentioned  above,  the 
principles  upon  which  depend  the  improvement  of  land  by  fallow, 
we  could  not  hope  to  obtain  favorable  results.  A  soil  of  great 
porosity,  through  which  water  penetrates  with  great  ease,  and 
which  does  not  yield  sufficient  hold  to  the  roots  of  plants,  and  also 
a  stiff  soil,  with  its  particles  too  finely  divided,  and  of  small  fer- 
tility on  account  of  its  physical  properties,  cannot  be  benefited  by 
the  mechanical  operations  of  the  field  ;  for  these  are  intended  to 
efliect  a  still  further  reduction  of  the  particles. 

The  physical  conditions  essential  to  the  fertility  of  a  soil  are 
usually  neglected  in  the  calculations  of  the  chemist,  and  thus 
render  a  mere  chemical  analysis  of  very  subordinate  value  ;  for 
the  existence  of  all  the  mineral  means  of  -lourishment  in  a  soil 
does  not  necessarily  indicate  its  value.  But  when  the  chemical 
is  combined  with  the  mechanical  analysis*  (for  the  latter  of  which 
Mr.  Rham  has  described  an  equally  simple  and  convenient  instru- 
ment), then  we  are  furnished  with  data  upon  which  to  form 
accurate  conclusions. 

•  The  estimation  of  the  unequal  quantities  of  mixed  ingredients,  such 
as  of  the  coarse  and  fine  sand,  and  of  the  clay  and  vegetable  matter? 


MINERAL  SUBSTANCES  IN  ANIMAL  BODIES.  I3i 


CHAPTER   XI. 

On  the  Rotation  of  Crops. 

It  has  been  shown,  by  accurate  examinations  of  animal  bodies, 
that  the  blood,  bones,  hair,  &c.,  as  well  as  all  the  organs,  contain 
a  certain  quantity  of  mineral  substances,  without  the  presence  of 
which  in  the  food,  these  tissues  could  not  be  formed. 

Blood  contains  potash  and  soda  in  combination  with  phosphoric 
acid  ;  the  bile  is  rich  in  alkalies  and  sulphur  ;  the  substance  of 
the  muscles  contains  a  certain  amount  of  sulphur  ;  the  blood 
globules  contain  iron  ;  the  principal  ingredient  of  bones  is  phos- 
phate of  lime  ;  nervous  and  cerebral  substance  contains  phos- 
phoric acid  and  alkaline  phosphates  ;  and  the  gastric  juice 
contains  free  muriatic  acid. 

We  know  that  the  free  muriatic  acid  of  the  gastric  juice  and 
part  of  the  soda  of  the  bile  is  obtained  from  common  salt  ; 
and  we  are  enabled,  by  the  mere  exclusion  of  this  material 
from  food,  to  put  an  end  to  the  digestive  process  and  life  of  an 
animal. 

When  a  young  pigeon  is  fed  upon  grains  of  wheat  in  which 
phosphate  of  lime,  the  principal  constituent  of  the  bones,  is  defi- 
cient, and  when  it  is  prevented  receiving  this  substance  from 
other  sources,  its  bones  become  thin  and  friable,  and  death  ensues 
if  the  supply  of  this  mineral  substance  is  still  prevented. 
(Choiset,  Report  to  the  Academy  of  Paris,  June,  1842.)  In 
like  manner,  if  we  exclude  carbonate  of  lime  from  the  food  of 
fowls,  they  lay  eggs  without  the  hard  exterior  shell. 

When  a  cow  is  fed  upon  an  excess  of  roots,  such  as  potatoes 
and  turnips,  the  same  thing  must  happen  to  it,  as  in  the  case  of 
the  pigeon  cited  above  ;  for  these  roots  contain  phosphate  of 
magnesia,  and  only  traces  of  lime.  Now,  if  we  remove  daily 
from  the  same  cow  a  certain  amount  of  phosphate  of  lime  in  its 


t34  ROTATION  OF  CROPS. 

milk,  without  restoring  this  in  the  food,  the  lime  will  be  obtained 
from  its  bones,  which  will  thus  lose  gradually  their  strength  and 
solidity,  until  they  are  no  longer  able  to  support  the  weight  of  the 
body.  But  if  we  give  to  the  pigeon  as  food  barley  or  peas,  and 
to  the  cow  barley-straw  or  clover,  we  will  be  able  to  sustain  th  -. 
health  of  the  animals  ;  for  these  materials  abound  in  salts  of 
lime.* 

Man  and  animals  receive  the  constituents  of  their  blood  and  of 
their  bodies  from  the  vegetable  world  ;  and  an  Infinite  Wisdonv 
has  so  ordained,  that  the  life  and  luxuriance  of  plants  is  strictly 
connected  with  the  reception  of  the  same  mineral  substances 
that  are  indispensable  for  the  development  of  the  animal  organ- 
ism ;  without  the  presence  of  the  inorganic  matters  found  in  the 
ashes  of  plants,  the  formation  of  the  germ,  leaves,  blossoms,  or 
fruit,  could  not  be  effected. 

The  amount  of  nutritive  matters  in  the  different  kinds  of  cul- 
tivated plants  is  very  unequal.  The  bulbous  plants  and  roots 
approach  each  other  much  more  nearly  in  their  chemical  consti- 
tuents than  they  do  the  seeds  ;  while  the  latter  possess  always 
an  analogous  composition. 

Potatoes,  for  example,  contain  from  75  to  77  per  cent,  of  water,, 
and  from  23  to  25  per  cent,  of  solid  matter.  By  means  of  a 
mechanical  process,  we  may  divide  the  latter  into  18  or  19  parts 
of  starch,  and  3  or  4  parts  of  a  fibre  resembling  starch.  Both  of 
these  added  together  weigh  nearly  as  much  as  the  dry  potatoe. 
The  two  per  cent,  not  accounted  for  consists  of  salts,  and  of  the. 
substance  containing  sulphur  and  nitrogen,  known  under  the, 
name  of  albumen. 

Beet  contains  from  88  to  90  per  cent,  of  water.     Five-and-  '■ 
twenty  parts  of  dry  beet  contain  very  nearly  the  same  elements 

*The  laborers. in  the  mines  of  South  America,  whose  daily  labor  (per- 
haps the  most  severe  in  the  world)  consists  in  carrying  upon  their  shoul- 
ders a  load  of  earth  of  from  180  to  200  lbs.  weight,  from  a  depth  of  450 
feet,  subsist  only  upon  bread  and  beans.  They  would  prefer  to  confine 
themselves  to  bread,  but  their  masters  have  found  that  they  cannot  work 
80  much  on  this  diet,  and  they,  therefore,  compel  them,  like  horses,  to  eat 
beans.- — {DarwirCs  Journal  of  Researches.)  Beans  are  proportionally 
much  richer  in  bone  earth  than  bread. 


CONSTITUENTS  OF  PLANTS.  135 

as  25  parts  of  dry  potatoes.  In  the  beet  there  are  18  or  19  part? 
of  sugar  and  3  or  4  parts  of  cellular  tissue ;  the  two  per  cent, 
not  accounted  for  consist  partly  of  salts,  and  the  remainder  of 
albumen. 

Turnips  contain  from  90  to  92  parts  of  water.  From  23  to  25 
parts  of  dry  turnips  contain  18  to  19  parts  pectin,  with  very 
little  sugar,  3  or  4  parts  cellular  tissue,  and  2  parts  salts  and 
albumen.  Sugar  and  starch  do  not  contain  nitrogen  ;  they  exist 
in  the  plant  in  a  free  state,  and  are  never  combined  with  salts,  or 
with  alkaline  bases.  They  are  compounds  formed  from  the  car- 
bon of  the  carbonic  acid  and  the  elements  of  water.  In  the 
potatoe,  these  assume  the  form  of  starch,  and  in  the  turnip  the 
form  of  pectin. 

In  the  seeds  of  cereals  we  find  vegetable  fibrin,  a  constituent 
containing  sulphur  and  nitrogen  ;  in  peas,  beans,  and  lentils,  we 
find  CASEIN  ;  and  in  the  seeds  of  oily  plants,  albumen  and  a 
substance  very  analogous  to  casein.  Casein  and  albumen  have 
the  same  composition  as  fibrin. 

Vegetable  fibrin  is  accompanied  by  starch  in  the  seeds  of  the 
cereals ;  the  latter  body  occurs  with  casein  in  leguminous 
plants ;  but,  in  the  oily  seeds,  its  place  is  supplied  by  another 
body  devoid  of  nitrogen,  such  as  oil,  butter,  or  a  constituent 
resembling  wax. 

It  is  obvious  that  we  must  furnish  to  plants  the  peculiar  con- 
ditions necessary  for  the  development  of  these  constituents, 
according  to  our  object  in  cultivation.  In  order  to  procure  sugar 
or  starch,  we  must  supply  the  plant  with  other  materials  than 
we  would  do  were  our  object  to  obtain  the  ingredients  containing 
sulphur  and  nitrogen. 

In  a  hot  summer,  when  the  deficiency  of  moisture  prevents 
the  absorption  of  alkalies,  we  observe  the  leaves  of  the  lime-tree, 
and  of  other  trees,  covered  with  a  thick  liquid  containing  a  large 
quantity  of  sugar  ;  the  carbon  of  this  sugar  must,  without  doubt, 
be  obtained  from  the  carbonic  acid  of  the  air.  The  generation 
of  the  sugar  takes  place  in  the  leaves  ;  and  all  the  constituents 
of  the  leaves,  including  the  alkalies  and  alka  ine  earths,  must 
participate  in  effecting  its  formation.  Sugar  does  not  exude  from' 
the  leaves  in  moist  seasons ;   and  this  leads  us  to  conjecture,  thatl 


136  ROTATION  OF  CROPS. 

the  carbon  which  appeared  as  sugar  in  the  former  case  would 
have  been  applied  in  the  formation  of  other  constituents  of  the 
tiee,  in  the  event  of  its  having  had  a  free  and  unimpeded  circu- 
lation. When  the  soil  is  frozen  in  winter,  there  cannot  be  an 
absorption  of  alkalies  by  the  roots  ;  but  notwithstanding  this,  it 
cannot  be  doubted  that  during  the  day  the  evergreen  and  the 
leaves  of  firs  and  pines  must  absorb  continually  from  the  air  car- 
bonic acid,  which  will  be  constantly  decomposed  by  the  action  of 
the  light.  When  circulation  is  unimpeded,  the  carbon  of  this 
carbonic  acid  may  perhaps  be  converted  into  wood  or  into  other 
constituents  of  the  plant ;  but,  in  the  absence  of  the  conditions 
necessary  for  this  conversion,  it  may  now  secrete  resin,  balsam, 
and  volatile  oils.  In  the  generation  of  the  sugar,  or  in  that  of 
resin  and  volatile  oil  in  the  firs  and  pines,  all  the  constituents  of 
the  leaves  must  take  part ;  and  hence  we  cannot  suppose  that 
their  alkalies,  their  lime,  &c.,  are  either  accidental,  or  that  they 
are  unnecessary  to  the  exercise  of  this  vital  function. 

For  the  conversion  of  the  carbon  or  carbonic  acid  into  sugar, 
it  is  necessary  that  certain  conditions  exist  in  the  plant  itself,  in 
addition  to  the  external  circumstances  (such  as  heat  and  air). 

We  furnish  the  conditions  essential  to  the  formation  of  starch, 
or  of  sugar,  when  we  supply  to  the  leaves — that  is,  to  the  organs 
destined  for  the  absorption  and  assimilation  of  the  carbonic  acid 
— their  necessary  constituents. 

The  sap  of  such  plants  as  are  rich  in  sugar  or  in  starch,  and 
also  the  sap  of  most  woody  plants,  contains  much  potash  and 
soda,  or  alkaline  earths.  We  cannot  suppose  that  these  are  mere 
accidental  ingredients  ;  on  the  contrary,  we  must  believe  that 
they  serve  some  purposes  of  the  plants,  and  that  they  assist  in 
the  formation  of  certain  of  their  constituents.  It  has  already 
been  mentioned,  that  they  exist  in  the  plants  in  a  state  of  com- 
bination with  certain  organic  acids.  These  acids  are  so  far 
characteristic  of  certain  genera,  that  they  are  never  absent  from 
them.  Hence  the  organic  acids  themselves  must  assist  in  some 
of  the  vital  functions.  Now,  when  it  is  remembered  that  unripe 
fruits,  such  as  grapes,  are  unfit  to  eat  on  account  of  their  acidity  ; 
that  these  fruits  possess  the  same  power  as  the  leaves  of  absorb- 
ing carbonic  acid,  and  of  giving  off  oxygen  on  exposure  to  light 


FORMATION  OF  SUGAR.  137 

(Saussure)  ;  and  further,  that  the  sugar  increases  on  the  diminu- 
tion of  the  acid  ;  we  can  scarcely  avoid  coming  to  the  conclusion, 
that  the  carbon  of  the  organic  acid  in  the  unripe  fruit  becomes  a 
constituent  of  the  sugar  when  it  is  ripe,  and  that,  in  consequence 
of  the  separation  of  oxygen  and  the  assimilation  of  the  constitu- 
ents of  water,  the  acid  passes  into  sugar. 

The  tartaric  acid  in  grapes,  the  citric  acid  in  cherries  and  in 
currants,  the  malic  acid  in  summer  apples,  which  ripen  on  the 
trees,  form  in  these  plants  the  intermediate  members  of  the  pas- 
sage of  carbonic  acid  into  sugar  ;  and  when  there  is  a  deficiency 
of  proper  temperature,  or  of  the  action  of  solar  light,  the  changes 
necessary  for  the  conversion  into  sugar  are  not  furnished,  and  the 
acids  remain. 

In  the  fruit  of  the  mountain  ash,  malic  acid  succeeds  the  tar- 
taric acid  at  first  present,  or  in  other  words,  an  acid  poor  in  oxy- 
gen succeeds  one  rich  in  that  element ;  afterwards  the  malic  acid 
in  the  berries  disappears  almost  entirely,  and  in  its  place  are 
found  gum  and  mucilage,  neither  of  which  formerly  existed  in 
them  ;  and  with  the  same  reason  that  we  consider  that  the  carbon 
of  the  tartaric  acid  forms  a  constituent  of  the  succeeding  malic 
acid — and  this  few  would  be  inclined  to  dispute — we  suppose  that 
the  carbon  of  the  acids  passes  over  into  the  sugar  which  succeeds 
on  their  disappearance. 

It  surely  cannot  be  supposed  that  a  plant  assimilates  carbonic 
acid,  and  that  this  carbonic  acid  is  converted  in  the  organism  of 
the  plant  into  tartaric,  racemic,  and  nitric  acids,  merely  for  the 
purpose  of  being  reconverted  into  carbonic  acid. 

If  then  the  view  be  confirmed,  that  the  organic  acids  in  culti- 
vated plants  aid  in  the  formation  of  sugar,  it  must  be  admitted 
that  they  are  of  equal  importance  in  the  production  of  all  other 
non-azotized  ingredients  similarly  composed.  The  formation  of 
starch,  of  pectin,  and  of  gum,  does  not  take  place  immediately,  that 
is,  they  do  not  arise  at  once  from  the  union  of  the  carbon  of  the 
carbonic  acid  with  the  constituents  of  water ;  but  a  gradual  con- 
version takes  place,  in  consequence  of  the  production  of  com- 
pounds that  are  always  poorer  in  oxygen,  and  always  richer  in 
hydrogen.     We  cannot  suppose  that  oil  of  turpentine  could  be 


138 


ROTATION  OF  CROPS. 


formed  without  the  existence  of  analogous  intermediate  members 
of  the  series. 

Now,  if  the  organic  compounds  rich  in  oxygen,  viz.  the  acids, 
be  the  means  of  producing  the  compounds  poorer  in  this  element, 
such  as  SUGAR,  STARCH,- &c.,  then  the  alkalies  and  alkaline  bases 
must  be  looked  upon  as  the  conditions  essential  for  the  formation 
of  these  non-azotized  constituents,  because  the  acids  existing  in 
cultivated  plants  are  generally  in  the  form  of  salts  and  are  rarely 
free.  An  organic  acid  may  perhaps  be  formed  without  the  pre- 
sence of  these  bases,  but,  in  the  absence  of  an  alkali,  or  of  a  body 
possessing  an  analogous  action,  sugar,  starch,  gum,  and  pectin, 
cannot  be  formed  in  the  organism  of  a  plant.  Sugar  is  not  formed 
in  those  fruits  and  seeds  in  which  the  organic  acids  are  free,  that 
is,  in  which  they  do  not  exist  as  salts,  as,  for  instance,  citric  acid 
in  the  lemon,  or  oxalic  acid  in  the  chick-pea.  It  is  only  in  plants' 
containing  the  acids  combined  with  bases  in  the  form  of  soluble 
salts,  that  sugar,  gum,  and  starch,  are  produced. 

It  is  a  matter  of  little  consequence  what  value  is  attached  to 
the  opinion  now  given  of  the  part  taken  by  alkaline  bases  in  the 
process  of  vegetable  life.  But  the  following  facts  are  of  the  great- 
est significance  and  value  to  agriculture,  namely,  that  the  newly, 
developed  sprouts,  leaves,  and  buds,*  or  in  other  words,  those 
parts  of  the  plants  possessing  the  greatest  intensity  of  assimilation, 
contain  the  greatest   proportion  of  alkaline  bases,  and  that  the 


*  1000  parts  of  Firwood  gave      3'28  parts  of  ashes. 
1000       «•         Fir-leaves    "    62-25 
The  ashes  of  the  leaves  of  the  fir  amount  to  more  than  20  times  those  in 
the  wood  freed  from  its  bark      100  parts  of  the  former  contain  : — (Hert- 
wig) 

Alkaline  carbonates  > 
Common  salt   -     -    > 
Sulphate  of  Potash 
Silicate  of  Potash 
Carbonate  of  lime    - 

*«  magnesia     - 

Phosphate  of  magnesia  ) 

"  lime         ) 

Basic  perphosphate  of  iron 
Basic  pnosphate  of  alumina 
Silica     -         -         -        - 


10-72 

1-95 
3-90 

G3-32  ] 
1-86 

6-35 

0-88 

0-71 

10-31 

12'70  salts  soluble  in  water. 


86'30  compound « insoluble  in  water 


IMPORTANCE  OF  ALKALIES.  139 

plants  richest  hi  sugar  and  in  starch  are  no  less  distinguished  for 
their  quantity  of  alkaline  hases  and  of  organic  acids. 

As  we  find  sugar  and  starch  accompanied  by  salts  of  an  or- 
ganic acid  ;  and  as  experience  proves  that  a  deficiency  of  alka- 
lies causes  a  deficient  formation  of  woody  fibre,  sugar,  and  starch  ; 
and  that,  on  the  contrary,  a  luxuriant  growth  is  the  consequence 
of  their  abundant  supply  ;  it  is  obvious  that  the  object  of  culture, 
viz.  a  maximum  of  crops,  cannot  be  obtained,  unless  the  alkalies 
necessary  for  the  transformation  of  carbonic  acid  into  starch  and 
sugar  are  supplied  in  abundant  quantity,  and  in  a  form  fit  for 
assimilation  by  plants.* 

*  The  acids — malic,  tartaric,  citric,  oxalic,  &,c. — are  generated  in  the 
organism  of  plants,  and  their  carbon  must  be  derived  from  carbonic  acid. 

In  plants  these  acids  are  found  combined  with  potash,  lime,  and  mag- 
nesia, in  the  form  of  salts,  the  smallest  particles  of  which,  when  left  to 
themselves,  follow  their  own  attractions ;  this  is  indicated  by  their  crys- 
tallization. 

There  is  no  doubt  that  these  compounds  do  not  possess  orginic  life,  be- 
cause the  active  power  observed  in  them  is  not  vitality,  but  cohesion. 
The  same  must  be  the  case  with  sugar,  which  crystallizes  in  a  similar  man- 
ner. 

We  must  presume  that  the  smallest  particles  of  the  products  formed 
from  carbonic  acid  are  subject  to  the  powers  acting  upon  them  in  the  living 
plant,  in  the  same  way  that  a  particle  of  carbonic  acid  is  ;  that,  therefore, 
the  carbon  of  oxalic  acid,  tartaric  acid,  &c.,  must  possess  the  power  of 
passing  into  a  constituent  of  an  organ  endowed  with  life. 

The  conversion  of  organic  acids  into  org  ms  may  be  followed  with  ease. 

If  we  suppose  that  1-2  equivalents  of  carbonic  acid,  in  the  presence  of  a 
base,  and  by  the  action  of  light,  loses  the  fourth  part  of  its  oxygen,  in  con- 
sequence of  the  action  of  vitality  upon  its  elements,  then  oxalic  acid  would 
be  produced.  In  its  anhydrous  state,  we  cannot  conceive  it  to  be  formed 
from  carbonic  acid  in  any  other  way. 

C  1  2  O2  4 — 08=C  1  2  Oi  8=6  Eq.  anhydrous  oxalic  acid. 

Oxalic  acid  does  not  exist  in  an  anhydrous  state.  Hydrated  oxalic  acid 
contains  one  equivalent  of  water;  the  oxalates  of  potash,  lime,  and  mag 
nesia  also  contain  water.     Hydrated  oxalic  acid  consists  of — 

C  1  2  Oi  8  +H6  06=C  12  Hfi  O2  4=6  Eq.  hydrated  oxalic  acid. 

From  this  it  may  be  observed  that  carbonic  acid  and  hydrated  oxalic  acid 
contain  the  same  quantity  of  oxygen.  We  can,  therefore,  suppose  that 
hydrated  oxalic  acid  has  been  formed  from  carbonic  acid,  to  which  a  cer- 
tain amount  of  hydrogen  has  been  added. 

By  the  continued  action  of  the  same  agents  a  new  quantity  of  oxygen 
mifjiit  become  separated  from  the  carbonic  acid,  in  which  case  tartaric  acid 


140  ROTATION  OF  CROPS. 


Every  part  and  constituent  of  the  body  is  obtained  from  plants. 
By  the  organism  of  the  plants,  are  formed  those  compounds  which 
serve  for  the  formation  of  the  blood  ;  there  can  be  no  doubt  that 

or  malic  acid  would  result.  By  the  separation  of  9  equivalents  of  oxygen, 
tartaric  acid  would  be  produced  ;  the  separation  of  12  equivalents  would 
produce  malic  acid. 

Hydrated  oxalic  acid  C  i  2  H  g  O  ^  4  — 0   9=Ci2H80i5  :=3  Eq.  tartaric  acid. 
"  "  CisH6024—Oi2=Ci2H60i2=3Eq.  malic  acid. 

By  the  simple  separation  of  water  from  the  elements  of  malic  acid  citric 
acid  is  produced  ;  we  know  that  we  can  produce,  by  means  of  heat,  aco- 
nitic  acid  from  citric  acid,  and  fumaric  acid,  or  maleic  acid,  from  malic 
acid. 

Malic  acid  C 1 2  H  e  0 1 2  —  HO=C  1 2  H  5  0 1  i  =3  Eq.  citric  acid. 
"  C12  He  Oi2— 3HO=Ci2  Hs  O9    =3  Eq.  fumaric  acid. 

Now  we  can  view  tartaric,  citric,  and  malic  acids  as  compounds  of 
oxalic  acid  with  sugar,  with  gum,  with  woody  fibre,  or  with  the  elements 
of  these : 

Tartaric  Acid.  Oxalic  Acid.  Dry  Sugar  of  Grapes. 

2(Ci2H60i3)  =  CijOxs  +  C12H12O12 
In  such  a  manner,  therefore,  that  the  addition  of  new  quantities  of  hydro- 
gen would  enable  all  these  acids  to  aid  in  the  formation  of  sugar,  starch, 
and  gum.  When  this  conversion  is  effected  the  alkalies  in  union  with 
the  acids  must  of  course  be  liberated,  and  they  will  thus  be  rendered  capa- 
ble of  playing  anew  the  same  part.  According  to  this  view,  it  is  quite 
conceivable  that  one  equivalent  of  an  alkali  may  enable  10,  20,  or  100 
equivalents  of  carbon  to  pass  into  constituents  of  a  plant;  but  the  time 
necessary  to  effect  the  transformation  will  vary  according  to  the  amount 
of  base  present. 

If  a  perennial  evergreen,  by  the  help  of  a  certain  quantity  of  alkali,  is 
able  to  assimilate  a  certain  amount  of  carbon  during  the  whole  year,  it  will 
be  necessary  to  convey  to  a  summer  plant  four  times  the  quantity  of  alk^li, 
in  order  to  enable  it  to  assimilate  the  same  amount  of  carbon  in  one-fourth 
the  time. 

Gay-Lussac  first  observed  that  by  the  contact  of  an  alkali,  at  a  high  tem- 
perature, with  tartaric,  citric,  and  oxalic  acids,  or  sugar,  woody  fibre,  &c., 
these  substances  were  reconverted  into  carbonic  acid. 

This  mode  of  decomposition  is  quite  the  reverse  of  that  which  takes 
place  in  plants  In  the  latter  the  elements  of  water  unite  with  the  com- 
pound of  carbon  (carbonic  acid);  and  oxalic  acid,  tartaric  acid,  &c.,  are 
thus  produced,  in  contsequence  of  a  separatioi*  or  ox  rcEiv.  But  in 
the  chemical  process  referred  to,  the  elements  of  the  water  unite  with  the 
elements  of  oxalic  and  tartaric  acids,  &c.,  and  they  are  reconverted  into 
carbonic  acid,  in  consequence  of  a  separation  of  hydrogen. 

Without  the  development  of  any  gas,  tartaric  and  citric  acids,  in  contact 
with  alkali,  even  at  a  temperature  of  400°  F.,  are  decomposed  into  oxalic 


IMPORTANCE  OF  ALKALIES.  141 

the  nutritive  parts  of  plants  must  contain  all  the  constituents  of 
the  blood,  and  not  merely  one  or  two  of  them. 

It  cannot  be  supposed  that  blood  will  be  formed  in  the  body  of 
an  animal,  or  milk  in  that  of  a  cow,  if  their  food  fail  in  even-ono 
of  the  constituents  necessary  for  the  sustenance  of  the  vital  func- 
tions. The  compounds  containing  nitrogen  and  sulphur,  as  well 
as  the  alkalies  and  phosphates,  are  constituents  of  the  blood  ;  but 
the  conversion  of  the  former  into  blood  cannot  be  conceived  with- 
out the  presence  and  co-operation  of  the  latter. 

According  to  this  view,  the  power  of  any  part  of  a  plant  to 
support  the  life  of  an  animal,  and  to  increase  its  blood  and  flesh, 
is  in  exact  proportion  to  its  amount  of  the  organic  constituents  of 
the  blood,  and  of  the  materials  necessary  for  their  conversion  into 
blood — viz.,  of  alkalies,  phosphates,  and  ehlorides  (common  salt 
or  chloride  of  potassium). 

It  is  highly  worthy  of  observation,  and  of  great  significance  to 
agriculture,  that  the  vegetable  compounds  containing  sulphur  and 
nitrogen,  which  we  have  designated  as  the  organic  constituents 
of  the  blood,  are  always  accompanied,  in  the  parts  of  the  plants 
where  they  occur,  with  alkalies  and  with  phosphates.  The  juice 
of  potatoes  and  of  beet  contains  vegetable  albumen  accompanied 
by  salts  of  alkaline  bases,  and  by  soluble  phosphate  of  magnesia  ; 
in  the  seeds  of  cereals  and  of  peas,  beans,  and  lentils,  there  are 
alkaline  phosphates  and  earthy  salts. 

The  seeds  and  fruits,  which  are  richest  in  the  organic  con- 
stituents of  the  blood,  contain  also  the  inorganic,  such  as  the  phos- 
phates, in  large  quantity  ;  other  parts  of  plants,  as  the  potatoe,  and 
the  various  roots,  which  are  proportionally  so  poor  in  the  former 
ingredients,  contain  a  much  smaller  quantity  of  the  latter. 

The  contemporaneous  occurrence  of  both  these  classes  of  com- 

and  acetic  acids.  Anhydrous  acetic  acid  contains  carbon  and  the  constitu- 
ents of  water,  in  exactly  the  same  relative  proportions  as  woody  fibre  (Pe- 
ligot),  which  also  yields  acetic  acid  under  similar  circumstances. 

These  methods  of  decomposition  have  induced  a  distinguished  French 
chemist  to  assume  the  existence  of  ready-formed  oxalic  acid  in  tartaric 
acid ;  certainly  its  elements  are  present,  besides  those  of  a  second  body, 
which,  like  sugar,  gum,  and  woody  fibre,  may  be  viewed  as  a  compouDd 
of  carbon  with  water.  ■X'^^'^'i 


143  ROTATION  OF  CROPS. 


pounds  is  so  constant,  that  it  would  be  difficult  to  trace  a  case  of 
more  intimate  connexion.  It  is  extremely  probable  that  th« 
origin  and  formation  of  the  organic  constituents  of  the  blood  in 
the  organism  of  plants  is  closely  connected  with  the  presence  of 
phosphates.  It  must  be  supposed  that  the  organic  constituents  of 
the  blood  will  not  be  formed  in  a  condition  adapted  for  their  con- 
version into  blood,  without  the  presence  of  alkalies  and  of  phos- 
phates, which  are  found  constantly  to  accompany  them  ;  and  this 
will  be  the  case,  even  although  carbonic  acid,  ammonia,  and  sul- 
phates as  a  source  of  sulphur,  be  presented  to  them  in  the  most 
abundant  quantity.  But,  even  on  the  assumption  that  they  could 
be  generated  in  the  organism  of  the  plant,  without  the  action  of 
these  substances,  we  cannot  suppose  that  they  could  be  converted 
into  blood  and  flesh  in  the  body  of  the  animals,  when  the  mineral 
constituents  of  the  blood  were  absent  from  the  vegetable  given 
as  food. 

But  independently  of  these  views,  a  rational  farmer  must  en- 
deavor to  effect  the  purpose  desired,  and  in  doing  so  he  must  act 
exactly  as  if  the  presence  of  the  inorganic  constituents  of  blood 
(the  alkalies  and  phosphates)  were  indispensable  for  the  produc- 
tion of  the  organic  constituents  ;  for  he  must  furnish  to  the  plants 
all  the  materials  necessary  for  the  formation  of  the  stem,  leaves, 
and  seeds.  If  he  is  desirous  of  making  his  land  yield  a  maximum 
of  blood  and  flesh,  he  must  furnish  to  it  in  abundant  quantity 
those  constituents  which  the  atmosphere  cannot  yield.* 

*  When  fresh  arterial  blood  is  evaporated  to  dryness*  and  incinerated, 
ashes  are  obtained  which  yield  to  water  salts  of  an  alkaline  reaction,  but 
not  any  alkaline  carbonates,  for  no  effervescence  is  occasioned  by  the  addi 
tion  of  an  acid.     These  ashes  consist  of  variable  quantities  of: — 
Phosphates  of  the  alkalies, 
Phosphate  of  lime, 
Phosphate  of  magnesia, 
Basic  perphosphate  of  iron 
Common  salt, 
Sulphates  of  the  alkalies. 
The  ashes  of  seeds  contain : — 

Bkans 
Peas,    (vicia  fab*), 
W\\\.       Buchner. 


Red 

White 

Wheat. 

Wheat. 

Rye. 

Fresenius. 

Will. 

Fresenius. 

Phosphate  of  potash 

-     36-51 

52-98 

52-91 

Phosphate  of  soda 

-     3213 

0-00 

9-27 

IMPORTANCE  OF  ALKALIES.  143 

Starch,  sugar,  and  gum  contain  carbon  and  the  elements  of 
water,  but  they  are  never  combined  with  alkalies,  nor  do  they 
contain  phosphates.  We  can  suppose  that  two  specimens  of  the 
same  plant,  when  supplied  with  the  same  amount  of  mineral  food, 
may  yet  form  very  unequal  quantities  of  sugar  and  of  starch ; 
and  that  two  equal  surfaces  of  land  prepared  in  exactly  the  same 
manner  may  bear  two  samples  of  barley,  the  one  of  which  may 
yield  half  or  double  the  weight  of  the  seeds  that  the  other  does. 
But  the  excess  of  weight  must  depend  upon  the  amount  of  unni- 
trogenous  ingredients,  and  not  on  the  constituents  containing  sul- 
phur and  nitrogen ;  for  if  the  same  quantity  of  the  inorganic 
constituents  of  blood  be  supplied  to  the  soil,  and  if  they  enter  into 
the  plants,  a  corresponding  quantity  of  the  organic  constituents 
of  blood  must  be  formed  in  the  seeds,  so  that  one  cannot  contain 
more  than  the  other.  A  difference  in  the  result  can  happen  only 
when  the  one  plant  receives  a  less  supply  of  nitrogen  than  the 
other,  in  a  given  time ;  for  when  there  is  a  deficiency  of  ammo- 
nia, a  corresponding  quantity  of  the  inorganic  constituents  of  the 
blood  is  lefl  unemployed. 

When  two  species  of  plants  are  cultivated  on  a  field  of  the 
same  nature  throughout,  that  species  which  generates  the  greatest 


Red 
Wheat, 
Fresenins. 

ViTHITE 

Wheat. 
Will. 

Rye. 
Fresenius. 

Peas. 
Will. 

Beans 

{viciafaba) 
Buchner. 

Phosphate  of  lime            -      3-35 
Phosphate  of  magnesia    -     19-61 
Perphosphate  of  iron       -      3  04 
Sulphate  of  potasl^    .    >  rp_ 
Common  salt      -         -    j  ^'^*^*'^' 

506 

32-96 

0-67 

5-21 

26-91 

1-88 

2-98 

10-77 
13-78 
2-46 
9-09  > 
3-96  5 

9-35 
19-11 

1-84 

Silicate  of  potash 

Silica        ....       0-15 

0-30 

0-34 

1-11 

's^    :    :    :]   -»'> 

8-03 

0-50 

In  the  above  analyses,  the  phosphates  of  the  alkalies  in  the  peas  and 
beans  are  contained  and  calculated  as  tribasic  salts  ;  those  in  the  seeds  of 
the  cereals,  as  bibasic.  The  ashes  of  the  seeds  cannot  effervesce  with 
acids,  because  they  do  not  contain  an  alkaline  carbonate ;  in  this  respect 
they  are  similar  to  the  ashes  of  blood  ;  and  it  may  be  observed  that  the 
salts  in  both  are  quite  the  same.  If  the  ashes  either  of  blood  or  of  the 
seeds  be  exposed  to  air,  they  absorb  caroonic  acid  and  moisture ;  the  tri- 
basic phosphate  becomes  bibasic,  and  the  third  atom  of  alkali  is  converted 
into  a  carbonate. 


144  ROTATION  OF  CROPS. 

quantity  of  the  organic  constituents  of  the  blood  (compounds  con- 
taining sulphur  and  nitrogen)  will  remove  from  the  soil  the 
greatest  amount  of  inorganic  constituents  (phosphates). 

The  one  plant  will  exhaust  a  soil  of  these  ingredients,  but  it 
may  still  remain  in  a  good  condition  for  a  second  kind  of  plant 
requiring  a  smaller  quantity  of  phosphates,  and  may  even  be  fer- 
tile for  a  third  kind. 

Hence  it  happens  that  the  greater  development  of  certain  parts 
of  plants,  such  as  the  seeds,  which  contain  much  more  of  the  or- 
ganic constituents  of  the  blood  than  any  of  the  other  parts,  exhausts 
and  Removes  fi'om  the  soil  a  much  greater  amount  of  phosphates 
than  would  be  done  by  the  culture  of  herbaceous  plants,  tubers, 
or  roots,  these  being  proportionally  much  poorer  in  the  above  in- 
gredients. It  is  further  evident,  that  two  plants  growing  togethex 
on  the  same  soil  will  share  its  ingredients  between  them,  if  they 
both  require  in  equal  periods  equal  quantities  of  the  same  con- 
stituents. The  ingredients  taken  up  into  the  organism  of  one  of 
the  plants  cannot  be  used  by  the  other. 

If  a  given  space  of  a  soil  (in  surface  and  in  depth)  contains 
inly  a  sufficient  quantity  of  inorganic  ingredients  for  the  perfect 
development  of  ten  plants,  twenty  specimens  of  the  same  plant, 
cultivated  on  this  surface,  could  only  obtain  half  their  proper  ma- 
turity ;  in  such  a  case,  there  must  be  a  difference  in  the  number 
of  their  leaves,  in  the  strength  of  their  stems,  and  in  the  number 
of  their  seeds. 

Two  plants  of  the  same  kind  growing  in  close  vicinity  must 
prove  prejudicial  to  each  other,  if  they  find  in  the  soil,  or  in  the 
atmosphere  surrounding  them,  less  of  the  means  of  nourishment 
than  they  require  for  their  perfect  development.  There  is  no 
plant  more  injurious  to  wheat  than  wheat  itself,  none  more  hurt- 
ful to  the  potatoe  than  another  potatoe.  Hence  we  actually  find 
that  the  cultivated  plants  on  the  borders  of  a  field  are  much  more 
luxuriant,  not  only  in  strength,  but  in  the  number  and  richness 
of  their  seeds  or  tubers,  than  plants  growing  in  the  middle  of  the 
•ame  field. 

The  same  results  must  ensue  in  exactly  a  similar  manne? 
when  we  cultivate  on  a  soil  the  same  plants  for  successive  years, 
instead  of,  as  in  the  former  case,  growing  them  too  closely  to- 


EXHAUSTION  OF  SOILS.  144 

gether.  Let  us  assume  that  a  certain  soil  contains  a  quantity  of 
silicates  and  of  phosphates  sufficient  for  lOOO  crops  of  wheat,  then, 
after  1000  years,  it  must  become  sterile  for  this  plant.  If  we 
were  to  remove  the  surface-soil  and  bring  up  the  subsoil  to  the 
surface,  making  what  was  formerly  surface-soil  now  the  subsoil, 
we  would  procure  a  surface  much  less  exhausted  than  the  for- 
mer, and  this  might  suffice  to  supply  a  new  series  of  crops,  but 
its  state  of  fertility  would  also  have  a  limit. 

A  soil  will  naturally  reach  its  point  of  exhaustion  sooner  the 
less  rich  it  is  in  the  mineral  ingredients  necessary  as  food  for 
plants.  But  it  is  obvious  that  we  can  restore  the  soil  to  its 
original  state  of  fertility,  by  bringing  it  back  to  its  former  com- 
position ;  that  is,  by  returning  to  it  the  constituents  removed  by 
the  various  crops  of  plants. 

Two  plants  may  be  cultivated  side  by  side,  or  successively 
when  they  require  unequal  quantities  of  the  same  constituents, 
at  different  times ;  they  will  grow  luxuriantly  without  mutual  in- 
jury, if  they  require  for  their  development  diffeueat  ingredients 
of  the  soil. 

The  experiments  of  Saussure,  and  of  many  other  philosophers, 
have  shown  that  the  seeds  of  beans,  of  Phaseo/us  vulgaris,  of  peas, 
and  of  garden  cresses,  germinate  and  even  grow  to  a  certain  ex- 
tent in  moist  sand  or  moistened  horse-hair  ;  but  when  the  mine- 
ral substances  contained  in  the  seeds  no  longer  suffice  for  their 
further  growth,  then  the  plants  begin  to  droop  ;  they  may  even 
perhaps  blossom,  but  they  never  bear  seeds. 

Wiegmann  and  Polstorf  allowed  plants  of  various  kinds  to 
vegetate  in  a  white  sand  previously  treated  with  aqua  regia,  and 
freed  from  the  acid  by  careful  washing,*  Barley  and  oats  grow- 
ing in  this  sand,  on  being  properly  treated  with  water  free  from 
ammonia,  reached  a  height  of  lA   foot;  thoy  blossomed,  but  did 

*This  sand  contained  in  1000  parts: — (Preisschrift,  p.  28.; 


Silica 

- 

, 

-    97yoo 

Potash 

, 

. 

3-20 

Alumina     - 

- 

8-76 

Peroxide  of  iron 

- 

315 

Lime 

- 

•        , 

4-84 

Magnesia 

8 

009 

148  ROTATION  OF  CROPS. 


not  come  to  seed,  and  withered  after  blossoming.  Vetches  reached 
a  height  of  ten  inches,  blossomed,  and  put  out  pods,  but  they  did 
not  contain  any  seeds. 

Tobacco  sowed  in  the  sand,  developed  itself  at  first  in  the  usual 
way,  but  from  June  to  October  the  plants  reached  the  height  only 
of  five  inches ;  they  had  only  four  leaves  and  no  stem. 

The  analysis  of  the  ashes  of  these  plants,  and  also  the  analysis 
of  their  seeds,  proved  that  although  this  sterile  sand  contained 
such  a  small  quantity  of  potash  and  of  soluble  constituents,  still 
it  had  yielded  a  certain  quantity  of  these,  and  on  this  quantity  the 
growth  of  the  leaves  and  of  the  stem  depended ;  but  it  was  im- 
possible that  the  plants  could  come  to  seed,  because  the  con- 
stituents necessary  for  the  formation  of  the  seeds  were  entirely 
absent. 

Phosphoric  acid  was  detected  in  the  ashes  of  most  of  the  plants 
growing  in  this  sand,  but  its  quantity  corresponded  only  to  that 
introduced  to  the  soil  in  the  seeds  themselves.  In  the  ashes  of 
the  tobacco  plant,  the  seeds  of  which  it  is  known  are  so  small  as 
to  contain  scarcely  an  appreciable  quantity  of  phosphoric  acid, 
not  a  trace  of  that  acid  could  be  detected. 

What  theory  distinctly  indicated  as  the  cause  of  the  sterility 
of  this  sand,  the  experiments  of  Wiegmann  and  Polstorf  com- 
pletely established.  They  took  the  same  sand  and  prepared  from 
it  an  artificial  soil  by  the  addition  of  salts  manufactured  in  a 
laboratory  (see  Appendix)  ;  they  then  sowed  in  this  soil  the  same 
])lants,  and  saw  that  they  flourished  in  the  most  luxuriant  man- 
ner. The  tobacco  became  three  feet  in  height,  and  put  forth 
many  leaves  ;  on  the  25th  of  June  it  began  to  blossom,  and  on  the 
10th  of  August  obtained  seeds,  from  which  on  the  8th  of  Septem- 
ber ripe  seed  capsules  with  complete  seeds  were  taken.  In  ex- 
actly the  same  way,  barley,  oats,  buck-wheat,  and  clover  grew 
luxuriantly,  blossomed,  and  yielded  ripe  nnd  perfect  seeds. 

It  is  quite  certain,  that  tiie  growth  of  these  plants  in  the  for- 
merly sterile  sand,  depended  upon  the  salts  added  to  it.  An  equa. 
fertility  for  all  plants  is  given  to  this  artificial  soil  by  the  addition 
of  certain  substances  which  are  absolutely  necessary  for  the  life 
of  the  plants,  because  they  are  present  in  the  matured  plant,  and 
in  its  stem,  leaves,  and  seeds. 


RESTORATION  OF  FERriLITY.  U7 

Thus  we  are  in  a  position  to  give  to  the  most  sterile  soil  a  state 
of  the  greatest  fertility  for  all  plants,  if  we  furnish  to  it  the  con- 
stituents which  they  require  for  their  growth.  It  would,  indeed, 
neither  repay  the  labor  nor  the  expense  to  render  fertile  on  those 
principles  an  absolutely  sterile  soil.  But  in  our  ordinary  arable 
soils,  which  contain  already  many  of  these  constituents,  it  suffices 
to  supply  the  absent  ingredients,  or  to  increase  those  which  are  in 
deficient  quantity.  At  the  same  time,  by  the  art  of  farming,  the 
soil  must  be  put  into  a  proper  physical  state,  by  which  it  is  ren- 
dered accessible  to  moisture  and  to  rain,  and  is  fitted  to  enable 
the  plants  to  appropriate  these  ingredients  of  the  soil. 

Different  genera  of  plants  require  for  their  growth  and  perfect 
maturity,  either  the  same  inorganic  means  of  nourishment,  al- 
though in  unequal  quantities  and  at  different  times,  or  they  re- 
quire different  mineral  ingredients.  It  is  owing  to  the  difference 
of  the  food  necessary  for  the  growth  of  plants,  and  which  must 
be  furnished  by  the  soil,  that  different  kinds  of  plants  exert  mutual 
injury  when  growing  together,  and  that  others,  on  the  contrary, 
grow  together  with  great  luxuriance. 

Very  little  difference  is  observed  in  the  composition  of  the  ashes 
of  the  same  plants,  even  although  they  have  grown  on  different 
soils.  Silica  and  potash  form  invariable  constituents  in  the  straw 
of  the  Graminese ;  and,  in  their  seeds,  there  is  always  present 
phosphate  of  potash  and  phosphate  of  magnesia.  A  large  quan- 
tity of  lime  occurs  in  the  straw  of  peas  and  in  clover.  We  know, 
further,  that  in  certain  kinds  of  plants,  the  potash  is  replaced  by 
soda,  and  the  lime  by  magnesia. 

It  has  been  shown  by  the  experiments  of  Boussingault,*  that 
the  five  following  crops  grown  in  succession  on  an  equal  surface 
of  the  same  field  once  manured,  removed  from  the  soil : — 

Ingredients  of  the  soil. 

1  Year  crop  of  Potatoes  (tubers  without  herb)  -         -     2168  lbs. 

2  "         "         Wheat  (straw  and  corn)    -         -         -         -     3710    " 

3  "         "  Clover G200    " 

4  «         «       CWheatf 48S-0    " 

( Fallow  Turnips lOSS    " 

4     "         "          Oats  (corn  and  straw)       ...         -    2150    " 

«f  ^Annales  de  Chimie  et  de  Physique,  t.  i  ,  p.  242 
t  On  a  system  of  alternate  crops. 


ii  ROTATION  OF  CROPS. 

'  ■  » 

Ingredients  of  the  soil 

By  a  crop  of  Beetroot*  (roots  without  leaves)     -         -         -  3996  " 

"         "     Peas  (peas  and  straw) olS'O  " 

"Rye 2S4-6  " 

"         ••     Helianthus  tuberosus 660*0  " 


These  numbers  express  the  quantities  (tt  inorganic  substances 
removed  from  the  same  soil  by  different  plants,  and  carried  away 
with  the  crops.  They,  therefore,  prove  that  different  plants  take 
up  into  their  organism,  unequal  weights  of  these  ingredients  of 
the  soil.  It  is  shown  by  a  further  consideration  of  the  composi- 
tion of  these  ashes,  that  they  differ  essentially  from  each  other 
with  respect  to  their  quality. 

One  thousand  parts  of  beet,  turnips,  or  potatoes,  yield  by  in- 
cineration 90  parts  of  ashes;  the  latter  are  easily  fusible,  and, 
contain  a  large  quantity  of  carbonate  of  potash,  and  of  salts  with 
alkaline  bases.     Of  these  90  parts,  75  parts  are  soluble  in  cold 
water. 

Two  thousand  parts  of  dry  fern  yield  also  90  parts  of  ashes  ; 
but  of  these  90  parts  none,  or  only  a  trace,  is  soluble  in  water 
(Berthier). 

The  ashes  of  wheat,  barley,  pea,  and  bean  straw,  differ  in  like 
manner  in  their  composition.  Equal  quantities  of  their  ashes 
contain  very  unequal  amounts  of  ingredients  soluble  in  water. 
There  are  certain  ashes  of  plants  wholly  soluble  in  water; 
others  are  only  partially  soluble,  while  certain  kinds  yield  only 
traces  of  soluble  ingredients. 

When  the  parts  of  the  ashes  Insoluble  in  water  are  treated 
with  an  acid  (muriatic  acid),  this  residue,  in  the  case  of  many 
plants,  is  quite  soluble  in  the  acids  (as  for  instance  the  ashes  of 
beet,  turnips,  and  potatoes)  ;  with  other  plants,  only  half  the 
residue  dissolves,  the  other  half  resisting  the  solvent  action  of  the 


*  In  the  above  five-yearly  rotation,  wheat  was  introduced  twice.  In  the 
second  year  the  crop  of  wheat  removed  from  the  soil  371  lbs.  and  in  the 
fourth  year  45S  lbs.  of  inorganic  substances.  This  difference  depends  upon 
the  unequal  quantities  of  straw  and  corn  in  the  crops  of  the  two  years. 
The  weight  of  the  straw  and  corn  of  one  year  was  8790  lbs.,  in  the  other 
year  it  amounted  to  10,858  lbs.  The  relative  proportion  of  their  ashes  if 
exactly  the  same. 


PLANTS  DISTINGUISHED  BY  CERTAIN  SALTS.  149 

acid ;  while  in  the  case  of  certain  plants  only  a  third,  or  even 
.ess  of  the  residue  is  taken  up  by  tlie  acid. 

Tlie  parts  of  the  ashes  soluble  in  cold  water  consist  entirely 
of  SALTS  WITH  ALKALINE  BASES  (poTASH  AND  soda).  The  ingre- 
dients soluble  in  acids  are  salts  of  lime  and  magnesia  ;  and 
the  residue  insoluble  in  acids  consists  of  silica. 

These  ingredients  being  so  different  in  their  behavior  to  watei 
and  to  acids,  afford  us  a  means  of  classing  the  cultivated  plants 
according  to  their  unequal  quantity  of  these  constituents.  Thus 
POTASH  PLANTS  are  those  the  ashes  of  which  contain  more  tlian 
half  their  weight  of  soluble  alkaline  salts  ;  we  may  designate  as 
LIME  PLANTS,  and  as  silica  PLANTS,  those  in  which  lime  and  silica 
respectively  predominate.  The  ingredients  thus  indicated  are 
those  which  form  the  distinguishing  characteristics  of  the  plants 
which  require  an  abundant  supply  of  them  for  their  growth. 

The  POTASH  PLANTS  include  the  chenopodia,  arrach,  worm- 
wood, 6zc.  ;  and  amongst  cultivated  plants,  the  beet,  mangel- 
wurzel,  turnip,  and  maize;  Tlie  lime  plants  comprehend  the 
lichens  (containing  oxalate  of  lime),  tlie  cactus  (containing  crys- 
tallized tartrate  of  lime),  clover,  beans,  peas,  and  tobacco. 
Silica  plants  include  wheat,  oats,  rye,  and  barley.* 


Salts  of  Potash  S;ilts  of  Lime 

an«l  Soila.  luiii  Magnesia.    Silica. 

[  Oatstraw  with  seeds  (1)      -     -34  00  4  00             02  00 

Silica    j  Wheat-straw  (2)       -     -     -     -  22  00  720             G105 

Plants.  1  Barlev-straw  with  seeds  (1)    -  lO'OO  2570             5503 

l^Rve-straw  (3) 18'65  10*52            03-89 


*  The  ashes  of  good  meadow-hay  (consisting;  of  a  mixtare  of  the  ashes 
of  potash,  lime,  and  silica  plants),  gave  in  100  parts — (Haioi.ev)  : 

Silica GO- 1 

Phosphate  of  lime  -         -         -         -     lOL 

Phosphate  of  peroxide  of  iron  -         -       50 

Lime      -         -         -         -         -         -         -       2-7 

Magnesia        -         -         -         -         -         -       8'6 

Gypsum         -         -         -         -         -        -1'2 

Sulphate  of  potash  -         -         -         -       2*2 

Chloride  of  pota-ssium     -        -        -         -       1'3 

Carbonate  of  soda  -        -        -        -      2*0 

Lobs 08 


190  ROTATION  OF  CROPS. 

Salts  of  Potash    Salts  of  Lime 
and  Soda.  and  Magnesia.      Silica. 

Tobacco  (Havannah)  (4)      -     -  2434  6744  8-30 

(Dutch)  (4)      -     -     -  23-07  62-23  15-25 


Lime 
Plants. ' 


(grovvn  in  an  arti-  )   _  ^  ^g.^^ 

I  soil  (1)  ) 


ficial  soil  (1) 


12-00 


Pea-straw  (4) 27  82  63-74               7-81 

Potatoe-herb  (5) 4  20  59-40             36  40 

Meadow-clover  (1)    -     -     -     -  39  20  56-00              4-90 

(Maize-straw  (2) 71  00  6  50             18*00 

Turnips      .......  81-60  18-40 

Beetroot  (6) 88  00  12-00 

Potatoes  (tubers)  (6)     -     .     -  85*81  14-19 

tHelianthus  tuberosus  (7)    -     -84-30  1570* 

This  classification,  however,  is  obviously  only  a  very  general 
one,  and  pennit-s  division  into  a  great  number  of  subordinate 
classes ;  particularly  with  respect  to  those  plants  in  which  the 
alkalies  may  be  replaced  by  lime  and  magnesia.  As  far  as  we 
are  authorized  to  judge  by  our  present  knowledge,  a  substitution 
of  soda  for  potasli  lakes  place  in  our  cultivated  plants  ;  but  it  has 
not  yet  jjcen  oi)served,  tliat  in  these  plants  the  alkalies  can  be 
replaced  by  lime. 

The  potutoe  ])lant  belongs  to  the  lime  plants,  as  far  as  regards 
the  ingredients  of  its  leaves,  but  its  tubers  (which  contain  only 
traces  of  lime)  belong  to  the  class  of  potash  plants.  With 
reference  to  tlic  siliceous  plants  this  difference  of  their  parts  is 
very  marked. 

Barley  must  be  viewed  as  a  lime  plant,  when  compared  with 
oats  or  with  wheat,  in  reference  to  their  ingredients  soluble  in 
muriatic  acid  ;  but  it  would  be  considered  as  a  siliceous  plant,  if 
viewed  only  in  reference  to  its  amount  of  silica.  Beet-root  con- 
tains phosphate  of  magnesia,  and  only  traces  of  lime  ;  while  the 
turnip  contains  phosphate  of  lime  and  only  traces  of  magnesia. 

"When  we  take  into  consideration  the  quantity  of  ashes,  and 
their  known  composition,  we  are  enabled  to  calculate  with  ease, 
not  only  the  particular  ingredients  removed  from  a  soil,  but  also 


In  the  above  analysis,  the  figures  represcrit  the  chemists  as  under:— 

(1)  Wiegmann  and  Polstorf.      I      (5)  Berth  i<»r  and  Braconnot. 

(2)  Saussure.  |      (6)  Hruschaner. 

(3)  Fresenius.  (7)  Braconnct. 

(4)  Hertwig. 


EXHAUSTION  OF  SOILS  BY  CERTAIN  PLANTS.  151 

the  degree  in  which  it  is  exhausted  of  these  by  certain  species 
of  plants  belonging  to  the  potash,  lime,  or  siliceous  plants. 
This  will  be  rendered  obvious  by  the  following  examples. 

A  soil,  consisting  of  four  Hessian  acres,  has  removed  from  it 
by  a  crop  of — 

Salts  of  potash  Salts  of  lime,  magnesia, 

and  soda.  and  jKjroxide  of  iron.  Silica, 

lbs.  lbs.  lbs.  lbs.  lbs. 

ixri        +(  In  straw       95"31  >    ,oA.r,  34"75  >     ai-rr  n^n.nr 

^^  ^^"^*  I  In  corn       35-20  ^^^  ""^  32-80  J    ^^  ^^          260-05 

n.^c      (  Tn  straw  150-40  >  .nQ.in  354-&0  >  „_,   .„             ,„  ^_ 

^'-^^      (  In  corn       44  02  \  ^^^  "^^  16-6S  5  ^'^-^^            ^^^® 

C  In  straw     40-73)     ^.^  „^  36  00) 

^y*^       ^  In  corn       4-2-05  5     ^^'^^  21-82  5                        ^ 

Beet-root,  without  leaves    -     -     36100  3784 

Heliiuithus  tuberosus      -     -     -     556-00  104-00 

The  same  surface  is  deprived  by  these  crops  of  the  following 
quantity  of  phosphates* — 

*  In  the  above  numbers  we  have  not  an  exact,  but  an  approximate,  pro- 
portion of  the  ingredients  of  the  soil  removed  by  the  various  crops.  The 
analyses  of  the  ashes  have  been  used,  as  far  as  they  are  already  made  and 
known.  The  analysis  of  the  ashes  of  the  seeds  and  of  the  straw  of  wheat 
is  by  Saussure  ;  that  of  pea-straw  by  Hertwig ;  that  of  peas  by  Dr.  Will ; 
that  of  the  ashes  of  the  straw  and  seeds  of  rye  by  Dr.  Fresenius,  of  the  beet- 
root by  Hruschauer,  and  of  Helianthus  tuberosus  by  Braconnot.  Exact 
and  trustworthy  results  can  only  be  obtained  by  estimating  the  ashes  of 
the  crops  grown  on  a  given  surface,  and  by  subjecting  these  ashes  to 
analysis ;  and  not  as  in  the  above  cases,  in  which  the  analyses  were  made 
upon  the  ashes  of  plants  grown  under  different  circumstances  and  in  differ- 
ent situations.  Boussingault,  for  example,  obtained  from  pea-straw  (from 
a  crop  heavily  manured)  11-2  per  cent,  of  ashes  ;  Saussure  obtained  only  8 
per  cent,  (in  straw  with  seeds),  and  Hertwig  only  5  per  cent.  These 
numbers  change  the  absolute  quantities,  but  have  little  or  no  influence  0;n 
the  relative  proportions. 

The  analyses  by  Sprengel  of  the  ashes  of  vai.ous  plants  are  quite  inexact, 
and  do  not  merit  the  slightest  confidence.  The  ashes  of  the  seeds  of 
wheat,  of  peas,  of  beans,  rye,  fcc,  consist  of  phosphates,  without  any  mix- 
ture of  carbonic  acid ;  these  ashes  do  not  contain  silica.  But  Sprengel 
finds  in  peas  18  per  cent,  and  in  rye  15  per  cent,  of  silica.  The  ashes  of 
the  seeds  of  rye  contain  48  per  cent.,  those  of  peas  34*23  per  cent.,  of  an- 
hydrous phosphoric  acid;  but  Sprengel  finds  in  peas  only  4  per  cent.,  in 
rye  8  per  cent.,  of  phosphoric  acid.  It  is  worthy  of  observation,  that  all 
the  bases  in  the  ashes  of  peas  are  present  as  tribasic  phosphates,  while  ia 
the  ashes  of  rye  and  ol  wheat,  they  exist  as  bibasic  salts. 


159  ROTATION  OF  CROPS. 


Helanthns 
Peas.*  Wheat.  Rye.  tuberosus.  Tamipa.f 

117  112-43  77-05  122  37-84 

According  to  the  preceding  views,  plants  must  obtain  from 
the  soil  certain  constituents,  in  order  to  enable  them  to  reach 
perfect  maturity — that  is,  to  enable  them  to  bear  blossoms  and 
fruit.  The  growth  of  a  plant  is  very  limited  in  pure  water,  in 
pure  silica,  or  in  a  soil  from  which  these  ingredients  are  absents 
If  there  be  not  present  in  the  soil  alkalies,  lime,  and  magnesia, 
the  stem,  leaves,  and  blossoms  of  the  plants  can  only  be  formed 
in  proportion  to  the  quantity  of  these  substances  existing  as  a 
provision  in  the  seed.  When  phosphates  are  wanting,  the  seeds 
cannot  be  formed. 

The  more  quickly  a  plant  grows,  the  more  rapidly  do  its 
leaves  increase  in  number  and  in  size,  and  therefore  the  supply 
of  alkaline  bases  must  be  greater  in  a  given  time. 

As  all  plants  remove  from  the  soil  certain  constituents,  it  is 
quite  obvious  that  none  of  them  can  render  it  either  richer  or 
more  fertile  for  a  plant  of  another  kind.  If  we  convert  into 
arable  land  a  soil  which  has  grown  for  centuries  wood,  or  a 
vegetation  which  has  not  changed,  and  if  we  spread  over  this 
soil  the  ashes  of  the  wood  and  of  the  bushes,  we  have  added  to 
that  contained  in  the  soil  a  new  provision  of  alkaline  bases,  and 
of  phosphates,  which  may  suffice  for  a  hundred  or  more  crops  of 
certain  plants.  If  the  soil  contains  silicates  susceptible  of  disin- 
tegration, there  will  also  be  present  in  it  soluble  silicate  of 
potash  or  soda,  which  is  necessary  for  the  rendering  mature  the 
stern  of  the  siliceous  plants ;  and,  with  the  pliosphates  already 
present,  we  have  in  such  a  soil  all  the  conditions  necessary  to 
sustain  uninterrupted  crops  of  corn  for  a  series  of  years. 

If  this  soil  be  either  deficient  or  wanting  in  the  silicates,  but 
yet  contain  an  abundant  quantity  of  salts  of  lime  and  of  phos- 
phates, we  will  be  enabled  to  obtain  from  it,  for  a  number  of  years, 
successive  crops  of  tobacco,  peas,  beans,  &c.,  and  wine. 

But,  if  none  of  the  ingredients  furnished  to  these  ulants  be  again 
returned  to  the  soil,  a  time  must  come  when  it  can  no  longer 

♦Heavily  manured.  t  Heavily  manured. 


EXHAUSTION  OF  SOILS.  K^3 


furnish  these  constituents  to  a  new  vegetation ;  when  it  must 
become  completely  exhausted,  and  be  at  last  quite  sterile,  even 
for  weeds. 

This  state  of  sterility  will  take  place  earlier  for  one  kind  of 
plant  than  for  another,  according  to  the  unequal  quantity  of  the 
different  ingredients  of  the  soil.  If  the  soil  is  poor  in  phosphates 
out  rich  in  silicates,  it  will  be  exhausted  sooner  by  the  cultivation 
of  ^♦'heat  than  by  that  of  oats  or  of  barley,  because  a  greater 
quantity  of  phosphates  is  removed  in  the  seeds  and  straw  of  one 
crop  of  wheat,  than  would  be  removed  in  three  or  four  crops  of 
oarley  or  of  oats.*  But  if  this  soil  be  deficient  in  lime,  the  bar- 
ley will  grow  upon  it  very  imperfectly. 

It  is  owing  to  the  deficiency  of  these  salts,  so  indispensable  to 
the  formation  of  the  seeds,  that  it  happens,  however  abundant  may 
be  the  quantity  of  silicates,  that  in  one  year  v.e  may  obtain  nine 
times,  in  a  second  thrice,  in  a  third  twice  as  much  corn  as  may 
grow  on  the  same  soil  in  another  year. 

In  a  soil  rich  in  alkaline  silioitos,  but  containing  only  a  limited 
supply  of  phosphates,  the  period  of  its  exhaustion  for  these  salts 
will  be  delayed  if  we  alternate  with  the  wheat  plants  which  we 
cut  before  they  have  come  to  seed ;  or,  what  is  the  same  thing, 
with  plants  that  remove  from  the  soil  only  a  small  quantity  of 
phosphates.  If  we  cultivate  on  this  soil  peas  or  beans,  these 
plants  will  leave,  after  the  removal  of  the  crop,  a  quantity  of  si- 
lica in  a  soluble  state  sufficient  for  a  Gucceeding  crop  of  wheat ; 
but  they  will  exhaust  the  coil  of  phosphates  quite  as  much  as 
wheat  itself,  because  the  seeds  of  both  require  for  their  maturity 
nearly  an  equal  quantity  of  these  salts. 

We  are  enabled  to  delay  the  period  of  exhaustion  of  a  soil  of 
phosphates  by  adopting  a  rotation,  in  which  potatoes,  tobacco,  or 
clover,  are  made  to  alternate  with  a  white  crop.  Tlie  seeds  of 
the  plants  now  named  are  small,  and  corAmn  proportionally  only 
minute  quantities  of  phosphates ;  their  rocts  and  leaves,  also,  do 
not  require  much  of  these  salts  for  their  maturity.     But  it  must 

*  The  weight  of  the  ashes  of  a  crop  ct  the  seeds  of  wheat  is  to  that  in  a 
rrop  of  oats  as  34 :  42'6,  the  pho3}.iliitp.s  contained  in  them  as  26 :  10 ;  th« 
phosphates  of  the  straw  not  being  included  in  the  calculation. 
8* 


154  ROTATION  OF  CROPS. 


be  remembered,  at  the  same  time,  that  each  of  these  has  ren- 
dered the  soil  poorer,  by  a  certain  quantity  of  phosphates.  By 
the  rotation  adopted,  we  have  deferred  the  period  of  exhaustion, 
and  have  obtained  in  the  crops  a  greater  weight  of  sugar,  starch, 
&;c.,  but  we  have  not  acquired  any  larger  quantity  of  the  con- 
stituents of  the  blood,  or  of  the  only  substances  which  can  be  con- 
sidered as  properly  the  nutritious  parts  of  plants.  When  the  soil 
is  deficient  in  salts  of  lime,  tobacco,  clover,  and  peas  will  not 
flourish ;  whilst,  under  the  same  conditions,  the  growth  of  beet- 
root or  turnips  will  net  be  impeded,  if  the  soil,  at  the  same  time, 
contain  a  proper  quantity  of  alkalies. 

When  a  soil  contains  silicates  not  prone  to  disintegrate,  it  may 
be  able,  in  its  natural  state,  to  liberate  by  the  influence  of  the  at- 
mosphere, in  three  or  four  years,  only  as  much  silica  as  suffices , 
for  one  crop  of  wheat.  In  this  case,  such  a  crop  can  only  be 
grown  on  it  in  a  three  or  four  years'  rotation,  assuming  that  the 
phosphates  necessary  for  tiie  formation  of  the  seeds  exist  in  the 
soil  in  suflicient  quantity.     But  we  can  shorten  this  period  by 

.  working  well  the  soil,  and  by  increasing  its  surface,  so  as  to  make 
it  more  accessible  to  the  action  of  the  air  and  moisture,  in  order 
to  disintegrate  the  soil,  and  to  procure  a  greater  provision  of  solu- 
ble silicates.  The  decomposition  of  the  silicates  may  also  be  ac- 
celerated by  the  use  of  burnt  lime  ;  Inr  it  is  certain  that,  although 
all  these  means  may  enable  us  to  ensure  rich  crops  for  a  certain 

,  period,  they  induce,  at  the  same  time,  an  earlier  exhaustion  of 
the  soil,  and  impair  its  natural  .stale  of  ftrtility. 

If  the  proportion  of  ailfali  and  of  silica  liberated  from  the  soil 
in  the  course  of  three  or  four  years  be  sufficient  only  for  one  crop 
of  wheat,  we  cannot  in  the  interval,  without  injury  to  this  crop, 
cultivate  on  the  same  soil  any  other  plant ;  because  the  alkalli 
necessary  for  the  grovv  th  of  the  latter  cannot  be  applied  to  the  use 
of  the  wheat. 

By  examining  the  known  proportion  of  alkali  and  of  silica 
liberated  by  the  disintegration  of  the  silicates  in  their  conversion 
into  clay,  and  by  the  weathering  of  the  latter  itself,*  we  find  that, 

*■  •One  equivalent  of  silica  is  libcratotl  for  every  equivalent  of  potash 
•eparftted  from  the  constituents  of  an  equivalent  of  felspar.     In  the  straW 


WEATHERING  OF  SILICATES.  155 


for  a  given  quantity  of  silica  rendered  soluble,  a  much  larger 
amount  of  alkali  is  liberated  than  corresponds  to  the  proportion  in 
which  both  arc  taken  up  into  the  straw  of  the  cereals. 

During  the  time  of  fallow,  which  in  this  case  must  elapse  be- 
fore two  crops  of  wheat  can  be  obtained,  we  may  employ  the  ex- 
cess of  alkalies  in  the  culture  of  other  plants  requiring  salts  with 
alkaline  bases  without  silica.  Between  these  crops,  therefore,  we 
may  grow  mangel  wurzel,  or  even  potatoes,  if  we  remove  only 
the  tubers  of  the  latter,  and  allow  the  plant  itself,  which  contains 
much  silica,  to  remain  on  the  field. 

In  the  preceding  remarks,  we  have  considered  the  changes  in 
the  nature  and  composition  of  a  field  on  which  a  rotation  of  culti- 
vated plants  has  been  carried  on  for  a  series  of  years.  If  this 
field  contain  an  ordinary  proportion  of  alkaline  silicates,  clay, 
lime,  and  magnesia,  it  will  possess  an  almost  inexhaustible  pro- 
vision of  alkalies,  alkaline  earths,  and  silica  ;  with  this  diiference, 
however,  that  they  are  not  all  in  a  fit  state  to  be  used  by  (he  plant 
at  the  same  time.  By  the  mechanical  operations  of  the  farm,  and 
by  chemical  means  (by  the  use  of  lime,  &c.),  we  may  shorten 
the  time  in  which  these  obtain  a  form  fitted  for  the  vital  functions 
of  the  plant ;  but  these  matters  do  not  suffice  for  its  complete 
maturity. 

When  phosphates  and  sulphates  are  absent  from  the  soil,  the 
plants  growing  on  it  cannot  form  seeds,  because  all  seeds,  without 
exception,  contain  compounds  in  which  phosphoric  acid  and  sul- 
phur are  invariable  constituents.  Although  all  the  other  ingre- 
dients of  plants  be  present  in  superabundance,  the  soil  will  become 
completely  sterile,  when  the  period  arrives  at  which  it  can  no 
longer  furnish  phosphates  or  sulphates  to  a  new  vegetation. 

We  must  suppose  that,  for  the  formation  of  the  stem  and  herb, 
for  the  fixation  of  carbon,  and  for  the  production  of  sugar,  starch, 
and  woody  fibre,  a  certain  amount  of  alkalies  (in  the  case  of  the 
potash -plants),  or  an  equivalent  of  lime  (in  the  case  of  the  lime- 
plants),  is  necessary.  But  we  must  bear  in  mind,  at  the  same 
time,  that  the  constituents  of  blood  can  be  formed  in  the  organism 

of  wheat,  oats,  and  rye,  for  10  eq.  of  silica,  there  is  only  1,  or  at  tbe  mart, 

a  eq  in  combination  with  alkalies. 


156  ROTATION  OF  CROPS. 

of  the  plant  only  in  quantity  corresponding  to  that  of  the  phos- 
phates, however  abundantly  ammonia  or  carbonic  acid  may  be 
supplied.  The  production  of  the  constituents  of  the  juice  con- 
taining sulphur  and  nitrogen  is  inseparably  connected  with  the 
presence  of  these  salts. 

Every  soil  upon  which  a  weed  attains  maturity  is  fitted  for 
culture  if  that  weed  yields,  on  incineration,  alkaline  ashes. 

The  alkalies  of  these  ashes  arise  from  silicates,  so  that  in  addi- 
tion to  the  alkalies,  soluble  silica  must  exist  in  the  same  soil. 
Such  a  soil  may  contain  a  quantity  of  pbosphates  of  lime  and 
magnesia  sufficient  for  potatoes  and  turnips,  without  on  that  ac- 
count being  rich  enough  for  crops  of  wheat. 

These  considerations  must  show  the  great  importance  which 
onght  to  be  attached  to  phosphates  in  the  practice  of  agriculture. 
These  salts  are  present  in  the  soil  only  in  small  quantity,  and 
therefore  the  greater  attention  should  be  paid  to  prevent  its  ex- 
haustion. 

In  the  limited  but  enormous  extent  of  the  ocean,  whole  worlds 
of  plants  and  animals  succeed  each  other.  A  generation  of  these 
animals  obtain  all  their  elements  from  plants,  and  the  constituents 
of  the  organs  of  the  animal  after  death  assume  their  original  form, 
and  serve  for  the  nourishment  of  a  new  generation  of  animals. 

The  oxygen  employed  by  the  marine  animals  in  the  process  of 
respiration,  and  removed  from  the  air,  dissolved  in  the  water 
(this  air  contains  from  .32  to  33  volumes  per  cent,  of  oxygen,  while 
atmospheric  air  contains  only  21  per  cent.),  is  restored  again  to 
the  water,  by  the  vital  processes  of  marine  plants.  In  the  pro- 
ducts of  the  putrefaction  of  the  carcases  of  the  dead  animals, 
their  carbon  is  converted  into  carbonic  acid,  their  hydrogen  into 
water,  and  their  nitrogen  assumes  again  the  form  of  ammonia. 

Thus,  we  observe  that  in  the  sea,  a  perpetual  circulation  takes 
place,  without  the  accession  or  removal  of  an  element,  and  this 
circulation  is  unlimited  in  its  duration,  allhou^h  it  may  be  in  its 
extent,  by  the  finite  quantity  of  nour":;r.n;<:n1  conteined  in  plants 
in  a  limited  space. 

Willi  respect  to  niarlre  ]-Iarttr:,  the.e  CAnnct  iio  any  discussion 
us  to  their  receiving  food  by  their  roots  in  the  form  of  humus. 
What  nourishment  indeed  can  the  thick  roots  of  the  giant  sea- 


FOOD  OF  MARINE  PLANTS.  157 


woed  draw  from  a  naked  rock,  the  surface  of  which  does  not  suffer 
the  slightest  change — a  plant  which  reaches  a  height  of  360  feet 
(Cook),  and  one  of  which,  with  its  leaves  and  twigs,  affords  nour- 
ishment to  thousands  of  marine  animals.  These  plants  require 
obviously  only  a  fastening  point  in  order  to  prevent  a  change  of 
place,  or  an  arrangement  by  which  their  small  specific  weight  is 
compensated  ;  they  live  in  a  medium  which  conveys  the  neces- 
sary nourishment  to  all  their  parts.  Sea-water  does  not  only  con- 
tain carbonic  acid  and  ammonia,  but  also  phosphates,  and  earthy 
and  alkaline  carbonates,  salts  invariably  found  in  the  ashes  of 
marine  plants,  and  indispensable  for  their  growth. 

All  our  knowledge  tends  to  prove  that  the  conditions  necessary 
for  the  existence  and  duration  of  marine  plants  are  the  same  as 
those  upon  which  the  existence  of  terrestrial  plants  depends. 

But  terrestrial  plants  do  not  live  like  marine  plants,  in  a  me- 
dium containing  all  their  elements,  and  surrounding  every  part 
of  their  organism  ;  but  their  existence  depends  upon  two  media, 
the  one  of  which,  the  so[L,  contains  constituents  which  are  absent 
from  the  other,  the  atmospheue. 

How  is  it  possible,  we  may  well  ask,  that  there  ever  could 
have  been  a  doubt  as  to  the  part  wliich  the  constituents  of  the  soil 
took  in  the  growth  of  the  vegetable  world  ?  Yet,  there  was  a 
time  when  it  was  considered  that  the  mineral  constituents  of 
plants  were  not  necessary  and  essential  to  their  existence  ! 

The  same  circulation  exists  on  the  surface  of  the  earth  as  in 
the  sea  ;  there  is  an  unceasing  change — a  perpetual  destruction 
and  re-establishment  of  equilibrium.  Practice  in  agriculture  has 
taught  us  that  the  amount  of  vegetable  matters  on  a  given  sur- 
face increases  with  the  supply  of  certain  substances,  which  were 

ORIGINAL    constituents    OF    THE    SAME    SURFACE   OF  THE  SOIL,  and 

had  been  removed  from  it  by  means  of  plants.  The  excrements 
of  men  and  of  animals  arise  from  plants  ;  they  are  exactly  the 
materials  which,  during  the  life  of  the  animal,  or  after  its  death, 
obtain  again  the  same  form  that  they  possessed  as  constituents  of 
the  soil. 

We  know  that  the  atmosphere  does  not  contain  these  materials, 
and  that  it  does  not  replace  them  ;  we  know  further  that,  by  their 
removal  from  the  soil,  an  inequality  of  production  is  occasioned, 


.58  ROTATION  OF  CROPS. 

and,  finally,  even  a  want  of  fertility  ;  but  that,  by  the  restoration 
of  these  materials,  the  fertility  may  be  sustained,  and  even  in- 
creased . 

After  so  many  striking  proofs  respecting  the  origin  of  the  con- 
stituents of  plants  and  of  animals,  and  of  the  use  of  alkalies,  of 
phosphates,  and  of  lime,  can  we  entertain  the  sliglitest  doubt  of 
the  principles  upon  which  a  rational  system  of  agriculture  must 
depend  ?  .^ 

Does  the  art  of  farming,  then,  depend  upon  anything  else  than 
the  restoration  of  a  disturbed  equilibrium  ? 

Is  it  conceivable,  that  a  rich  fertile  land,  with  a  flourishing 
trade,  which  has  for  centuries  exported  the  products  of  its  soil  in 
the  form  of  cattle  and  of  corn,  can  retain  its  fertility,  if  the  same 
trade  do  not  restore  to  its  land,  in  the  form  of  manure,  the  con-, 
stituents  abstracted  from  it,  and  which  cannot  be  replaced  by  the 
atmosphere  ?  In  such  a  case,  would  not  the  same  fate  await  this 
land  as  that  which  befel  Virginia,  upon  the  soil  of  which  wheat 
and  tobacco  can  no  longer  be  cultivated  ?  .^ 

In  the  large  towns  of  England,  the  products  of  English  as  well 
as  of  foreign  agriculture  are  consumed  ;  and  to  supply  this  great 
consumption,  the  constituents  of  the  soil  necessary  to  the  plants 
are  removed  with  them,  from  an  immense  surface  of  land,  to 
which  they  are  not  again  returned.  The  domestic  arrangements 
peculiar  to  the  English  render  it  difficult,  perhaps  even  impossi- 
ble, to  collect  the  immense  quantity  of  phosphates  (the  most  im- 
portant ingredients  of  the  soil,  although  present  in  it  in  small 
quantity),  which  are  daily  sent  into  the  rivers  in  the  form  of  urine 
and  of  solid  excrements.  We  have  seen  ujwn  the  fields  of  Eng- 
land exhausted  of  their  phosphates,  the  most  beneficial  effects  pro- 
duced upon  the  crops  by  the  introduction  of  bones  (phosphate  of 
lime)  from  the  Continent ;  in  some  cases,  the  crops  on  the  soil 
were  doubled  by  the  use  of  this  manure,  as  if  by  a  charm. 

But  if  this  exportation  of  bones  be  continued  on  the  same  scale 
as  at  present,  the  German  soil  will  become  gradually  exhausted ; 
and  the  loss  will  be  perceived  to  be  greater  than  at  first  is  ap- 
parent, when  it  is  considered  that  a  single  pound  weight  of  bones 
contains  as  much  phosphoric  acid  as  a  whole  hundred- weight 
of  corn. 


WASTE  OF  MANURE  IN  ENGLAND. 


Thousands  of  hundred  weights  of  phosphates  flow  annually  into 
the  sea  with  the  Thames,  and  with  other  of  the  British  rivers. 

Thousands  of  hundred-weights  of  the  same  materials,  arising 
from  the  sea,  annually  flow  back  again  into  that  land  in  the  form 
of  guano. 

In  the  alchemistical  era,  the  imperfect  knowledge  of  the  pro- 
perties of  matter  gave  rise  to  the  supposition,  that  metals,  such  s 
gold,  could  be  developed  by  seeds.  Crystalline  forms,  and  the 
ramifications  which  they  assume,  appeared  to  alchemists  to  be  the 
leaves  and  branches  of  metallic  plants,  and  their  great  endeavors 
were  to  find  an  earth  fitted  for  the  peculiar  growth  and  develop- 
ment of  their  seeds.  Without  there  being  any  apparent  nourish- 
ment given  to  a  seed,  it  was  seen  to  grow  to  a  plant,  which  put  forth 
blossoms  and  seeds.  This  led  to  the  belief,  that  could  the  seeds 
of  metals  be  procured,  similar  hopes  of  their  reaching  maturity 
might  be  entertained. 

Such  ideas  could  only  belong  to  a  time  when  scarcely  anything 
was  known  of  the  nature  of  the  atmosphere,  and  when  there  was 
not  a  conception  of  the  part  taken  by  the  earth  and  air  in  the  vital 
processes  of  plants. 

The  chemistry  of  the  present  day  exhibits  the  elements  of 
water ;  it  can  even  prepare  this  water  with  all  its  properties  from 
their  elements  ;  but  it  cannot  manufacture  these  elements — it  can 
only  prepare  them  from  water.  The  newly-formed  water,  which 
has  been  artificially  prepared,  was  water  previously  to  the  separa- 
tion of  its  elements. 

Many  of  our  farmers,  like  to  these  alchemists  of  old,  in  search- 
ing after  the  philosopher's  stone,  look  now  to  find  the  wonderful 
seeds  ;  for  they  expect  that  tiieir  land  should  bear  a  hundred- 
fold, without  supplying  to  it  any  food,  even  although  this  land 
is  scarcely  rich  enough  to  bear  the  plants  usually  cultivated 
on  it  ! 

The  experience  of  centuries  or  of  thousands  of  years  is  not 
sufficient  to  protect  them  from  the  new  fallacies  which  are  con- 
stantly arising  ;  the  power  of  resisting  the  effects  of  credulity  or 
superstition  can  only  be  obtained  from  a  knowledge  of  true  scien- 
tific principles. 

In  the  first  stage  of  the  philosophy  of  nature,  it  was  supposed 


160  ROTAflON  OF  CROPS. 


that  the  organic  kingdom  was  developed  from  water  alone  ;  then 
it  was  considered  that  both  water  and  air  were  necessary  ;  and 
now  we  know,  with  the  greatest  certainty,  that  the  soil  furnishes 
other  important  conditions,  which  must  be  added  to  the  former, 
otherwise  plants  will  not  obtain  the  power  of  propagating  and 
of  multiplying  themselves. 

The  quantity  of  food  for  plants  in  the  atmosphere  is  limited, 
but  still  it  must  be  sufficient  to  cover  the  surface  of  the  earth  with 
a  rich  vegetation. 

In  the  tropics,  and  in  those  regions  of  the  earth  where  a  favor- 
able soil,  moisture,  light,  and  an  elevated  temperature— the  usual 
conditions  of  fertility — are  combined,  the  vegetation  is  scarcely 
confined  by  the  space  on  which  it  grows ;  there,  when  the  soil  is 
deficient,  the  bark  and  branches  of  dead  plants  soon  form  soil  fdr 
succeeding  ones.  It  is  obvious,  therefore,  that  there  is  no 
deficiency  of  atmospheric  food  for  the  plants  of  these  regions, 
and  there  can  be  none  for  our  own  cultivated  plants. 

The  constant  movement  to  which  the  atmosphere  is  subjected, 
causes  an  equ^il  distribution  of  the  gaseous  food  necessary  for 
the  growth  of  plants,  so  that  the  tropics  do  not  contain  more 
of  it  than  the  cold  zones  ;  and  yet,  how  different  appears 
to  be  the  power  of  production  of  equal  surfaces  of  land  in  these 
regions  ! 

All  plants  of  tropical  regions,  such  as  the  sugar-cane,  the 
palms  bearing  wax  and  oil,  contain,  in  comparison  with  our  own 
cultivated  plants,  only  a  small  quantity  of  the  constituents  of 
blood  necessary  for  the  nourishment  of  animals.  The  produce 
in  tubers,  of  an  acre  of  potatoes,  growing,  as  in  Chili,  to  the 
height  of  a  tall  bush,  would  scarcely  suffice  to  prolong  the  life 
of  an  Irish  family  for  a  day  (Darwin).  The  nutritious  plants 
which  are  the  objects  of  culture,  are  only  a  means  for  generating 
the  necessary  constituents  of  tlie  blood.  If  the  ingredients  of  the 
soil  indispensable  to  their  formation  be  absent  from  it,  the  consti- 
tuents of  the  blood  cannot  be  formed  in  the  plants,  although  it  is 
possible  that  wood,  sugar,  or  starch,  might  be  produced  under 
such  circumstances.  If  we  desire  to  produce  from  a  given  sur- 
face more  of  these  constituents  of  the  blood,  than  the  plants 
growing  on  it  could  receive  from  the  atmosphere  or  from  the  soil 


TROPICAL  VEGETAtlON.  1«1 

in  their  natural  wild  and  normal  condition,  we  must  procure  an 
artificial  atmosphere,  and  we  must  add  to  the  soil  the  ingredients 
in  which  it  is  deficient; 

Very  unequal  quantities  of*  nourl.^hment  must  be  furnished  to 
diflerent  plants  in  a  given  time,  in  order  to  procure  a  free  and 
unimpeded  growth.  On  arid  sands,  simple  calcareous  soils,  or  on 
naked  rocks,  few  plants  flourish j  and  those  that  do  are  generally 
perennial.  These,  growing  slowly,  require  only  small  quanti- 
ties of  mineral  ingredients,  so  that  soils  sterile  for  other  kinds  of 
plants  are  still  able  to  furnish  to  them  mineral  ingredients  in 
sufficient  quantity.  The  apnuals,  particularly  summer  plants, 
reach  complete  maturity  in  comparatively  a  short  time,  so  that 
they  do  not  flourish  on  a  soil  poor  in  the  mineral  substances  ne- 
cessary for  their  growth. 

The  food  contained  in  the  atmosphere  does  not  suflice  to 
enable  these  plants  to  obtain  their  maximum  of  size  in  the  short 
period  of  their  life.  If  the  object  of  culture  is  to  be  attained, 
there  must  be  present  in  the  soil  itself  an  artificial  atmosphere 
of  carbonic  acid  and  ammonia,  and  this  excess  of  nourishment, 
which  the  leaves  cannot  get,  must  be  conveyed  to  corresponding 
organs  existing  in  the  soil. 

But  the  ammonia  with  carbonic  acid  does  not  suffice  to  enable 
itself  to  become  a  constituent  of  a  plant  fit  for  the  food  of  animals. 
Albumen  cannot  be  formed  without  alkalies,  and  vegetable  fibrin 
and  casein  cannot  be  produced  without  the  aid  of  phosphoric  acid 
and  of  earthy  salts.  We  know  tliat  phosphoric  acid  is  indis- 
pensable for  the  production  of  the  seeds  of  our  cereals  and  culi- 
nary vegetables,  although  the  same  ueid  is  found  in  large  quan- 
tity in  an  excrementitious  form  in  ihe  bark  of  woody  plants. 

How  very  different,  in  comparison  with  summer  plants,  are 
the  characters  of  evergreens,  of  mosses,  ferns,  and  pines  ! 
During  every  part  of  the  day,  both  in  summer  and  in  winter, 
they  absorb  by  their  leaves  carbonic  acid,  which  the  sterile  soils 
cannot  yield  :  their  fleshy  leather-like  leaves  retain  with  great 
tenacity  the  water  absorbed,  and  lose  very  little  of  it  by  evapora- 
tion, in  comparison  with  other  plants.  And  yet  how  very  small 
is  the  quantity  of  mineral  substances  which  they  abstract  from 
the  soil  during  the  whole  year  of  almost  perpetual  growth,  when 


162  ROTATION  OF  CROPS. 

we  compare  it  with  the  quantity  removed  from  the  soil  in  three 
months  by  a  crop  of  wheat  of  equal  weight  ! 

It  follows,  then,  from  the  preceding  observations,  that  the  ad- 
vantage of  the  alternate  system  of  husbandry  consists  in  the  fact 
that  the  cultivated  plants  abstract  from  the  soil  u'lequal  quantities 
of  certain  nutritious  matters. 

A  fertile  soil  must  contain  in  sufficient  quantity,  and  in  a  form 
adapted  for  assimilation,  all  the  inorganic  materials  indispensable 
for  the  growth  of  plants. 

A  field  artificially  prepared  for  culture,  contains  a  certain 
amouiit  of  these  ingredients,  and  also  of  ammoniacal  salts  and  de- 
caying vegetable  matter.  The  system  of  rotation  adopted  on  such 
a  field  is,  that  a  potash-plant  (turnips  or  potatoes)  is  succeeded  by 
a  silica  plant,  and  the  latter  is  followed  by  a  lime-plant.  All  these 
plants  require  phosphates  and  alkalies — the  potash-plant  requiring 
the  largest  quantity  of  the  latter  and  the  smallest  quantity  of  the 
former.  The  silica  plants  require,  in  addition  to  the  soluble  silica 
left  by  the  potash  plants,  a  considerable  amount  of  phosphates; 
and  the  succeeding  lime-plants  (peas  or  clover)  are  capable  of 
exhausting  the  soil  of  this  important  ingredient  to  such  an  extent, 
that  there  is  only  sufficient  left  to  enable  a  crop  of  oats  or  of  rye 
to  form  their  seeds. 

The  number  of  crops  which  may  be  obtained  from  the  soil  de- 
pends upon  the  quantity  of  the  phosphates,  of  the  alkalies,  or  of 
lime,  and  the  salts  of  magnesia  existing  in  it. 

The  existing  provision  may  suffice  for  two  successive  crops 
of  a  potash  or  of  a  lime-plant,  or  for  three  or  four  more  crops  of 
a  silica  plant,  or  it  may  suffice  for  five  or  seven  crops  of  all  taken 
together  ;  but  after  tiiis  time,  all  the  mineral  substances  removed 
from  the  field  in  the  form  of  fruit,  herbs,  or  straw,  must  again  be 
returned  to  it  ;  the  equilibrium  must  be  restored,  if  we  desire  to 
retain  the  field  in  its  original  state  of  fertility. 

This  is  efiected  by  means  of  manure.  It  may  be  assumed  that 
the  soil  receives  again,  in  the  roots  and  stubble  of  the  cereals,  or 
in  the  fallen  leaves  of  Irees,  as  much  carbon  as  its  humus  yielded 
in  the  form  of  carbonic  acid  at  the  commencement  of  a  new  vege- 
tation ;  in  like  manner,  the  herb  of  the  potatoe  and  the  roots  of  the 
clover  renTiain  in  th<»  soil.     The  remains  of  these  plants  enter  into 


RESTORATION  OF  THE  INGREDIENTS  OF  THE  SOIL.      103 


decay  during  winter,  and  thus  furnish  to  the  young  plant  a  new 
source  of  carbonic  ncid.  The  soil,  therefore,  is  not  exhausted  of 
its  humus  by  the  cultivation  of  these  plants. 

It  may  also  be  deduced  from  theoretical  considerations,  that  the 
soil  receives  during  the  life  of  the  plants  as  much,  or  perhaps 
even  more,  of  carbonaceous  materials  as  it  yields  to  them  ;  and 
that  the  soil  is  enriched  in  these  matters  by  the  process  of  secre- 
tion proceeding  at  the  surface  of  the  fibres  of  the  root ;  the  mat- 
ters thus  secreted  enter  into  decay  during  winter,  and  pass  into 
humus. 

Physiologists  differ  in  their  opinions  with  regard  to  the  pro- 
cesses of  secretion  and  excretion  by  plants  ;  some  affirm  that  these 
processes  do  exist,  while  others  deny  their  existence  ;  so  that,  at 
this  moment,  the  opinions  are  divided  on  the  subject.  But  still, 
no  one  denies  that  the  oxygen  separated  by  the  leaves  and  green 
parts  of  plants  ought  to  be  considered  as  an  excrement.  In  the 
act  of  vital  activity,  the  plants  assimilate  the  carbon  of  carbonic 
acid,  and  the  hydrogen  of  water,  making  them  constituents  of  their 
organs,  while  they  separate  part  of  the  oxygen  with  which  these 
elements  were  combined. 

In  the  blossoms  we  find  volatile  oils,  compounds  rich  in  carbon 
and  in  hydrogen,  and  which  are  not  further  employed  in  any  of 
the  vital  processes  :  out  of  the  bark  we  see  flowing  resin,  balsam, 
and  gum  ;  and  out  of  the  leaves,  sugar  and  mucilaginous  sub- 
stances. 

Oxygen  is  not  separated  from  the  surface  of  the  bark,  roots,  or 
other  parts  that  are  not  green  ;  but,  on  the  contrary,  these  parts 
separate  substances  rich  in  carbon  which  have  been  generated  by 
the  vital  processes  of  the  plant,  but  have  not  experienced  any 
further  change. 

When  we  compare  the  barks  of  the  fir,*  pine,  beech,  or  oak,  • 


*  Ashes  of  Wood  of  Ashes  of  the  Bt.  '< 

the  Fir.  of  the  Fir. 

Hertw'g.  Hkrtwig. 

1000  wood  gave  '^•2S  ashes.  1000  bark  gave  1785  ashea 

{Carbonate  of  soda     -     -     7-42 
Carbonate  of  potash      -1130         Soluble  saita  2-95 
Chloride  of  sodium      )   r^ 
Sulphate  of  pot  I  h       5    '  ^""^^^ 


164 


ROTATION  OF  CROPS. 


with  their  sap  and  wood,  we  find  that  they  differ  essentially  from 
each  other,  both  in  their  composition  and  characters. 

True  wood  yields  only  one-fourth  to  two  per  cent,  of  ashes, 
while  the  bark  of  the  oak,  fir,  willow,  and  beech,  gives  6,  10,  to 
15  times  more.  The  ashes  of  wood  and  of  the  bark  have  a  very 
different  composition.  The  inorganic  ingredients  of  the  bark 
are  obviously  inorganic  substances  expelled  by  the  living  or- 
ganism. 

The  same  reasoning  holds  good  in  the  case  of  the  organic  sub- 
stances as  it  docs  in  the  case  of  the  bark.  The  bark  of  the  cork- 
tree  contains  nearly  half  its  weight  of  fats,  or  of  fatty  substances, 
which  we  also  find  present,  although  in  smaller  proportion,  in  the 
bark  of  firs  and  pines.  The  solid  material  (insoluble  in  alcohol 
or  ether)  of  these  barks  is  entirely  different  from  woody  fibre. 
The  barks  of  firs  and  pines  are  completely  soluble  in  potash  leys, 
forming  a  liquid  of  a  dark  brown  color,  which  yields,  on  the  ad- 
dition of  an  acid,  a  precipitate  strongly  resembling  the  substance 
called  humic  acid.     But  wood  is  not  attacked  by  potash  ley. 

These  barks  are  in  so  far  true  excrements,  that  they  arise  from 
living  plants,  and  play  no  further  part  in  their  vital  functions  ; 
they  may  even  be  removed  from  them,  without  thereby  endanger- 
ing their  existence.  It  is  known  that  certain  trees  throw  off  an- 
nually their  barks  :  this  circumstance,  viewed  in  its  proper  light, 
shows  that,  during  the  formation  of  certain  products  formed  by  the 
vital  processes,  materials  arise  which  are  incapable  of  experien- 
cing a  further  change. 


Ashes  of  Wood  of 

Ashes  of  the  Bark 

the  Fir. 

of  the  Fir. 

Hkrtwiq. 

Hertwio. 

'  Carbonate  of  lime    -     -     50  94     - 

-  64-98' 

Magnesia        .     -     -     .       5  00     - 

-     0-93 

Phosphate  of  lime    -     -       3-43     - 

-     503 

magnesia-       2-90     - 

-     4  18 

isoluble 
Salts. 

"              manganese    Traces  - 

- 

Insoli  ble 

peroxide  of  >     ^^    _ 
iron      -    5  *  "* 

-     104 

Salts  9  7-05 

"              alumina    -       115    - 

-     2  42 

Silica            -         .         -     13-37     - 

-  17-2S 

^Loss     -        -         -         -      ;>-26     - 

-     1-79 

100-00 


100  00 


BARK  VIEWED  AS  EXCRKMENTITIOUS  Ifl/V 

There  is  every  reason  to  believe  that  this  separation  takes  place 
over  the  whole  surface  ;  it  is  observed  not  only  on  the  stem,  but 
also  on  the  smallest  twigs ;  and  hence  we  must  conclude  that  the 
same  excretory  process  goes  on  in  the  roots. 

When  a  branch  of  a  willow  is  allowed  to  vegetate  in  rain-water, 
the  latter  assumes  gradually  a  dark-brown  color.  The  same 
phenomenon  is  observed  in  bulbous  plants  (such  as  hyacinths) 
allowed  to  grow  in  pure  water.  It  therefore  cannot  be  denied 
that  excrements  are  actually  separated  by  plants,  although  it  is 
very  possible  that  they  do  not  all  separate  them  in  the  same 
degree. 

It  is  generally  admitted  by  farmers,  as  the  result  of  experience, 
that  a  soil  is  enriched  in  organic  matters  by  the  culture  tf  peren- 
nial plants,  such  as  sainfoin  and  lucerne,  which  are  distinguished 
for  the  extensive  ramification  of  their  roots  and  strong  gro^vth  of 
their  leaves  ;  the  cause  of  their  enriching  power  will  perhaps  be 
explained  from  the  above  remarks. 

We  cannot  effect  the  formation  of  ammonia  on  our  cultivated 
land,  but  it  is  in  our  power  to  obtain  an  artificial  production  of 
humils:  this  must  be  viewed  as  one  of  the  objects  of  a  system  of 
rotation,  and  as  a  second  cause  of  the  advantage  arising  from  it. 

By  sowing  a  field  with  a  fallow  crop,  such  as  clover,  rye, 
lupins,  buck-wheat,  &c.,  and  by  ploughing  and  incorporating  with 
the  soil,  the  plants,  when  they  have  nearly  come  to  blossom,  we 
procure  to  the  young  plants  of  a  new  crop  sown  on  the  field  a 
maximum  of  nourishment  and  an  atmosphere  of  carbonic  acid,  in 
consequence  of  the  decay  of  the  preceding  crops.  All  the  nitro- 
gen drawn  from  the  atmosphere  by  the  preceding  plants,  and  all 
the  alkalies  and  phosphates  received  from  the  soil,  now  serve  to 
cause  a  luxuriant  growth  to  the  plants  which  succeed. 


166  ON  MANURE. 


CHAPTER  XII. 

On  Manure. 

In  order  to  obtain  clear  ideas  on  the  value  and  action  of  ani- 
mal  excrements,  it  is  most  important  to  bear  in  mind  their  origin. 
It  is  wcU  known,  that  when  a  man  or  an  animal  is  deprived  of  food, 
he  becomes  cnaciated,  and  his  body  diminishes  in  weight  from 
day  to  day.  This  emaciation  becomes  visible  after  a  few  days ;' 
and  in  the  case  of  persons  who  are  starved  to  death,  their  fat  and 
muscular  substance  disappear,  their  body  becomes  empty  of 
blood,  and  at  last  nothing  remains  except  skin  and  bones. 

On  the  other  hand,  the  weight  of  the  body  does  not  alter,  even 
though  supplied  with  sufficient  food  ;  for  in  the  body  of  a  healthy 
man  there  is  neither  a  marked  increase  nor  diminution  of  weight 
from  one  twenty-four  hours  to  another. 

These  phenomena  prove  with  certainty  that  a  change  proceeds 
in  the  rganism  of  an  animal  during  every  moment  of  its  life ; 
and  a  part  of  the  living  substance  of  the  body  passes  out  from  it 
in  a  state  more  or  less  changed.  The  weight  of  the  body,  there- 
fore, would  decrease  continually,  if  the  parts  separated  or  changed 
were  not  again  prepared  and  replaced. 

The  restoration  and  replacement  of  the  original  weight  is 
effected  by  means  of  food. 

A  man  or  an  animal  consumes  daily  a  certain  number  of  oun- 
ces, or  of  pounds  of  bread,  flesh,  or  other  nutritive  substances, 
so  that  in  a  year  he  consumes  an  amount  of  food  of  a  much 
greater  weight  than  that  of  his  own  body.  He  takes  in  the  food 
a  certain  quantity  of  carboi,  hydrogen,  oxygen,  nitrogen,  and 
sulphur,  as  well  as  a  very  considerable  quantity  of  mineral  in- 
gredients, which  we  have  learned  to  know  as  the  ashes  of  food. 

What,  it  may  be  asked,  has  become  of  all  these  constituents 
of  the  food,  to  what  purposes  have  they  been  applied,  and  in 


FOOD  UNDERGOES  COMBUSTION  IN  THE  BODY.  1*7 

what  form  have  they  been  expelled  from  the  body  ?  Carbon  and 
hydrogen  have  been  furnished  to  the  body,  and  yet  the  weight  of 
the  body,  with  respect  to  these  elements,  has  not  increased  :  the 
body  has  received  in  the  food  a  quantity  of  alkalies  and  of  phos- 
phates, but  still  the  amount  of  these  substances  in  our  body  has 
not  been  rendered  greater. 

These  questions  are  easily  solved,  when  it  is  considered  that 
the  food  does  not  supply  the  only  conditions  necessary  for  the 
support  of  the  viiui  processes,  for  there  are  other  conditions 
which  distinguish  animals  essentially  from  plants. 

The  life  of  an  animal  is  essentially  connected  with  a  continual 
introduction  into  its  system  of  the  oxygen  contained  in  air. 
Without  ai/  and  oxygen,  animals  cannot  exist.  In  the  process  of 
respiration,  a  certain  quantity  of  oxygen  is  introduced  into  the 
blood  by  means  of  the  lungs.  The  air  which  we  respire  contains 
this  oxygen,  and  yields  it  to  the  constituents  of  the  blood ;  the 
blood  of  an  adult  man  removes  from  the  air,  at  each  respiration, 
about  two  cubic  inches  of  oxygen.  A  man  consumes  in  24  hours, 
from  10  to  14  ounces  of  oxygen — in  a  year,  hundreds  of  pounds  ; 
what  then  becomes  of  this  oxygen  ?  We  take  into  our  bodies 
pounds  weight  of  food  and  pounds  weight  of  oxygen,  and  never- 
theless the  weight  of  our  body  either  does  not  increase  to  any 
sensible  extent,  or  it  does  so  in  a  much  smaller  proportion  than 
corresponds  to  the  food  :  in  certain  individuals  (in  old  age)  it 
experiences  a  continued  reduction. 

It  must  be  obvious,  that  this  phenomenon  is  explicable  only  on 
the  supposition  that  the  oxygen  and  the  constituents  of  the  food 
exercise  on  each  other  in  the  organism  a  certain  action,  in  con- 
sequence of  which  both  disappear  from  the  body.  This  is  actu- 
ally the  case ;  for  none  of  the  oxygen  respired  as  a  gas  into  the 
body  remains  in  it ;  it  is  separated  in  the  form  of  carbonic  acid 
and  water.  The  carbon  and  hydrogen,  which  have  combined 
with  the  oxygen,  are  derived  from  the  organism  ;  but  as  these  ele- 
ments of  the  body  are  obtained  from  the  food,  it  may  be  said, 
that,  in  their  final  form,  all  the  elements  of  food  capable  of  uniting 
with  oxygen  are  converted,  in  the  living  body,  to  oxygenized 
compounds,  or,  what  expresses  the  same  thing,  they  enter  into 
combustion. 


ON  MANURE. 


When  bread,  flesh,  potatoes,  hay,  or  oats,  are  burned  in  a  com- 
mon fire-place,  with  an  ordinary  draught,  but  perfectly  exposed  to 
the  entrance  of  the  air,  the  carbon  of  these  substances  is  con- 
verted into  carbonic  acid,  their  hydrogen  into  water,  their  nitro- 
gen is  set  at  liberty  in  the  form  of  ammonia,  and  their  sulphur 
assumes  the  form  of  sulphuric  acid,  so  that  at  last  nothing  re- 
mains except  the  mineral  ingredients  of  these  substances  in  the 
form  of  ashes.  In  the  form  of  volatile  products,  we  obtain  car- 
bonic acid,  carbonate  of  ammonia,  and  water,  and  besides  these 
(if  the  combustion  be  incomplete),  smoke  or  soot ;  in  the  incom- 
bustible residue  we  obtain  all  the  salts  contained  in  tiie  tbod. 

When  water  is  poured  over  these  ashes,  the  alkalies  dissolve, 
and  also  the  soluble  phosphates,  common  salt,  and  sulphates ; 
the  residue,  insoluble  in  water,  contains  salts  of'  lime  and  magne- 
sia, and  silica,  if  the  substance  burned  contained  the  latter  sub- 
stance. 

Exa.'itly  the  same  process  ensues  in  the  bodies  of  animals. 
Through  the  skin,  and  by  means  of  the  lungs,  the  carbon  and 
hydrogen  of  the  food  are  expelled  in  their  final  form  of  carbonic 
acid  and  water ;  all  the  nitrogen  of  the  food  is  collected  in  the 
urinary  bladder  in  the  form  of  urea,  which  by  the  simple  union  of 
the  elements  of  water  is  converted  into  carbonate  of  ammonia. 

When  the  body  regains  its  original  weight,  exactly  as  much 
carbon,  hydrogen,  and  nitrogen,  as  it  took  in  the  food,  must  have 
been  expelled  from  it.  It  is  only  in  youth,  and  in  the  process  of 
fattening,  that  an  increase  in  weight  takes  place,  and  that,  there- 
fore, part  of  the  constituents  of  the  food  remains  in  the  body :  in 
old  age,  on  the  contrary,  the  weight  decreases,  that  is,  more  is 
separated  from  the  body  than  enters  into  it. 

The  nitrogen  of  the  food  is,  therefore,  daily  expelled  by  the 
urine  in  the  form  of  urea  and  of  compounds  of  ammonia.  The 
faeces  contain  the  unburned  substances  of  the  food,  such  as  the 
woody  fibre,  chlorophyl,*  and  wax,  which  have  suffered  no 
change  in  the  organism ;  the  carbon,  hydrogen,  and  nitrogen  of 
these  substances  are  very  small  in  quantity,  in  comparison  with 


*  Chlorophyl  is  the  green  coloring  matter  of  the  leaves  and  other  parta 
ef  plants. 


ASHES  OF  FCK)D  OBTALNED  FROM  SOILS.  169 


.hat  in  the  food.  The  mixture  of  these  indigestible  materials 
with  the  secretions  may  be  compared  to  the  smoke  and  sooi 
produced  when  food  is  imperfectl}'  burned  in  a  common  fire- 
1)1  ace. 

It  has  been  shown,  by  an  examination  of  faeces  and  of  urine,  that 
tlie  mineral  ingredients  of  the  food,  the  alkalies,  salts,  and  silica, 
are  eliminated  in  these  excrements.  Urine  contains  all  the  solu- 
ble mineral  substances  of  the  food,  while  the  faeces  contain  the 
ingredients  insoluble  in  water.  As  the  food  is  burned  in  the 
body  just  as  it  would  be  in  a  fire-place,  the  urine  may  be  said  to 
contain  the  soluble  salts  of  the  ashes,  and  the  fieces  the  insoluble 
salts. — (Sec  Appendix.)     A  horse 

CONSUMKa    Of   INORKDIKNTS    OF   THK    SOIL—  AND    THE    EXCRKMKNTS    RETURN — 

Ounces  of  Ashet*.  Ounces  of  Ashes. 

In  I51bs.  hay*    . 
In  4-5-t  oats 

In  its  drink  . 


1801)  In  urine     .      3-51  >  .-,,.0-, 

2-40  S  21-40       In  faeces     .    18.36  5"'^' 
0-42  > 


A.    COW— 

(;-67) 

In  urine     . 

12-29 

20-20  >  28-47 

In  faeces     . 

,      16-36 

JO    S 

In  milk 

1-SO 

In  30  lbs.  of  potatoeM    . 

In  hay  .  ...    -20-20^28-47        In  faeces     .      16-36^30-45 

In  its  drink     . 

These  analyses  show,  as  nearly  as  can  be  expected  from  ex- 
periments of  this  kind,  that  all  the  con^ituents  of  the  ashes  of 
the  food  are  again  obtained,  without  alteration,  in  the  solid  and 
liquid  excrements  of  the  horse  and  cow.  The  action  produced 
upon  our  fields,  by  the  liquid  and  solid  excrements  of  animals, 
ceases  to  be  mysterious  or  enigmatical,  as  soon  as  we  have  at- 
tained a  knowledge  of  their  mode  of  origin. 

The  mineral  ingredients  of  food  liave  been  obtained  from  our 
fields,  having  been  removed  from  them  in  the  form  of  seeds, 
of  roots,  and  of  herbs.  In  the  vital  processes  of  animals,  the 
combustible  elements  of  the  food  are  converted  into  compounds 
of  oxygen,  while  the  urine  and  tiie  faeces  contain  the  constituents  of 
the  soil  abstracted  from  our  fields  ;  so  that,  by  incorporating 
these  excrements  with  our  land,  we  restore  it  to  its  original  state 
of  fertility.  If  they  are  given  to  a  field  deficient  in  ingredients 
necessary  for  the  growtli  of  plants,  it  will  be  rendered  fertile  for 
all  kinds  of  crops. 

•  Bonssin^nult,  Annales  de  Chimie  et  de  Physique,  Xxxi 
0 


1%  ON  MANURE. 


A  part  of  the  crop  taken  from  a  fielJ  is  used  in  feeding  and 
fattening  animals,  which  are  afterwards  consumed  by  man. 
Another  part  is  used  directly  in  the  form  of  potatoes,  meal,  or 
vegetables ;  while  a  third  part,  consisting  of  the  remnants  of 
plants,  are  employed  as  litter  in  the  form  of  straw,  &c.  It  is  evi- 
dent that  all  the  constituents  of  the  field  removed  from  it  in  the 
form  of  animals,  corn,  and  fruit,  may  again  be  obtained  in  the 
liquid  and  solid  excrements  of  man,  and  in  the  bones  and  blood 
of  the  slaughtered  animals.  It  altogether  depends  upon  us  to  keep 
our  fields  in  a  constant  state  of  composition  and  fertility  by  the 
careful  collection  of  these  substances.  We  are  able  to  calculate 
how  much  of  the  ingredients  of  the  soil  are  removed  by  a  sheep, 
by  an  ox,  or  in  the  milk  of  a  cow,*  or  how  much  we  convey 
from  it  in  a  bushel  of  barley,  wheat,  or  potatoes.  From  thje 
known  composition  of  the  excrements  of  man,  we  are  also  able  to 
calculate  how  much  of  them  it  is  necessary  to  supply  to  a  field 
to  compensate  for  the  loss  that  it  has  sustained. 

It  is  certainly  the  case,  that  we  could  dispense  with  the  excre- 
ments of  man  and  animals,  if  we  were  able  to  obtain  from  other 
sources  the  ingredients  on  which  depends  all  their  value  for  agri- 
culture. It  is  a  mafter  of  no  consequence  whether  we  obtain 
ammonia  in  the  form  of  urine,  or  in  that  of  a  salt  from  tlie  pro- 
ducts of  the  distillation  of  coal ;  or  whether  we  obtain  phos- 
phate of  lime  in  the  form  of  bones,  or  as  the  mineral  apatite.  The 
principal  object  of  agriculture  is  to  restore  to  our  land  the  sub- 
stances removed  from  it,  and  which  the  atmosphere  cannot  yield; 
in  whatever  way  the  restoration  can  be  most  conveniently  effected. 

•  1000  parts  of  milk  yielded,  by  incineration — 

1 67-7  Residue. 

II 490 

100  parts  of  the  ashes  of  the  milk  consisted  of : — 

Phosphate  of  lime    . 
"  magnesia 

Perphosphate  of  iroa 
Chloride  of  potassium 
Co  iimoa  salt 
Sotla 


I. 

II. 

.       .  47-14 

50-81 

.       .     8.57 

9.45 

.       .     1.43 

1-04 

.       .  a9-39 

27-03 

.       .     4-89 

5" 

.     .    s  r)7 

()  (',  I 

99-9S 

i;>«v)!)j 

phosphate;  or  food  restored  by  excrements,   r.i 

If  the  restoration  be  imperfect,  the  fertility  of  our  fields,  or  of 
the  whole  country,  will  be  impaired  ;  but  if,  on  the  contrary,  we 
add  more  than  we  take  away,  the  fertility  will  be  increased. 

The  importation  of  urine  or  of  solid  excrements  from  a  foreign 
land,  is  quite  equivalent  to  the  importation  of  corn  and  cattle. 
All  these  matters,  in  a  certain  time,  assume  the  form  of  corn, 
flesh,  and  bones  ;  they  pass  into  the  bodies  of  men,  and  again  as- 
sume the  same  form  which  they  originally  possessed.  The  only 
true  loss  that  we  experience,  and  that  we  cannot  prevent,  on  ac- 
count of  the  habits  of  our  times,  is  the  loss  of  tlie  phosphates, 
which  man  carries  in  his  bones  to  the  grave.  The  enormous 
quantity  of  food,  which  man  consumes  during  the  sixty  years  of 
his  life,  and  every  constituent  of  it  that  was  derived  from  our 
fields,  may  again  be  obtained  and  restored  to  tiiem.  It  is  quite 
certain,  that  it  is  only  in  the  bodies  of  our  youth,  and  in  those  of 
growing  animals,  that  a  certain  quantity  of  phosphate  of  lime  is 
retained  in  the  bones,  and  of  alkaline  phosphates  in  the  blood. 
With  the  exception  of  this  extremely  small  proportion,  in  coni- 
parison  with  the  actual  quantity  existing  in  the  food,  all  the  salts 
with  alkaline  bases,  and  all  the  phosphates  of  lime  and  magne- 
sia, which  animals  daily  consume  in  their  food, — in  fact,  there- 
fore, all  the  inoro;anic  ingredients  of  the  food, — are  again  obtained 
in  the  solid  and  liquid  excrements.  Without  even  instituting  an 
analysis  of  these  excrements,  we  can  with  ease  indicate  their 
quantity  and  their  nature,  and  we  can  estimate  their  composition. 
We  furnish  to  a  horse  daily  4^  lbs.  of  oats  and  15  lbs.  of  hay  ; 
the  oats  yield  4  per  cent.,  the  hay  9  per  cent,  of  ashes  ;  aiid  from 
these  data  we  calculate,  that  the  daily  excrements  of  the  horse 
must  contain  21  ounces  of  inorganic  materials,  which  have  been 
obtained  from  our  fields.  The  analyses  of  the  ashes  of  hay  and 
of  oats  inform  us  in  per  centage  how  much  silica,  alkalie*  •^d 
phosphates  are  contained  in  them.* 

•  The  ashes  of  oats  contain,  according  to  Saussure — 

In  100  parts. 
Soluble  salts  with  alkaline  bases         -         -     16 
Phosphate  of  lime  ^      -        -         -        -     -    24 
Silica 60 

The  Mhes  of  hay  contain,  according?  to  Hajdlkjt — 


ITS  ON  MANURE. 


The  nature  of  the  fixed  ingredients  in  the  excrements  varies 
according  to  the  food.  If  we  feed  a  cow  on  mangel-wurzel,  or 
potatOGvS,  without  hay  or  barley  straw,  its  solid  excrements  will 
not  contain  silica,  but  they  will  contain  phosphates  of  lime  and 
magnesia,  and  the  liquid  excrements  will  contain  carbonates  of 
potash  and  soda,  and  also  compounds  of  these  bases  with  inorganic 
acids.  If  the  fodder  or  food  yield,  on  incineration,  ashes  contain- 
ing soluble  alkaline  phosphates  (such  as  bread,  meal,  all  kinds 
of  seeds  and  flesh),  we  obtain  from  the  animal  fed  upon  these, 
urine  in  which  the  alkaline  phosphates  exist.  But  if  the  ashes 
of  the  food  (such  as  hay,  turnips,  and  potatoes),  do  not  contain 
any  soluble  phosphate  of  the  alkalies,  but  only  insoluble  earthy 
phosphates,  then,  the  urine  is  free  from  the  alkaline  phosphates, 
and  the  faeces  are  found  to  contain  the  earthy  phosphates.  The 
urine  of  men  and  of  animals  subsisting  upon  flesh  and  grain  con- 
tains  alkaline  phosphates  ;  while  that  of  animals  living  wholly 
upon  grass  is  destitute  of  these  salts.  The  analyses  of  human 
excrements,*  those  of  birds  living  upon  fish  (guano),    and  of 

In  lUO  parts. 
Phosphate  of  lime  -         -         -         -     16  1 

Perphosphate  of  lime  -      -        -        .  5'0 

Liioe 2-7 

Magnesia  ------  8"6 

Sulphate  of  soda     -        -        -        -        -       1*2 

••  potash      -        -        -         -  22 

Chloride   of  potassium    -        -        -       -      1*3 

Carbonate  of  soda       -        -        -        -  Vl 

•*         potash  -         -         -        -       0'9 

Silica      -     -         -         -         -         -       -  60'6 

Loss 0-8 

•  According  to  tlie  analysis  of  Berzelius,   1000  parts  of  human  urine 
contain — 

1000  p»rt«  of       1000  parts  of 
Urioe.  the  residue. 

Urea 3010  44-39 

Free  lactic  acid,  lactate  of  ammonia,  and^ 

animal  matters   not  separable   from  >i  71 4  25.J>S 

them        -        «        -        -        -        -  S 

Uric  acid      -         -        .         -         -         -100  1-49 

Mucus  of  the  bladder    .        .        »        .       0*32  0*48 

Sulphate  of  potash        ....      3*71  5*54 

"  soda 316  4-72 


EXCREMENTS  RESTORE  ASHES  OF  PLANTS.  173 

the  excrements  of  the  horse  and  of  the  cow  (see  Appendix), 
yield  conclusive  proof  of  the  nature  of  the  salts  contained  in 
them. 

In  the  solid  and  liquid  excrements  of  man  and  of  animals,  we 

RESTORE    TO   OUR   FIELDS    THE    ASHES  OF  THE    PLANTS  which  SerVcd 

to  nourish  these  animals.  These  ashes  consist  of  certain  soluble 
salts  and  insoluble  earths,  which  a  fertile  soil  must  yield,  for  they 
are  indispensable  to  the  growth  of  cultivated  plants. 

It  cannot  admit  of  a  doubt,  that,  by  introducing  these  excre- 
ments to  the  soil,  we  give  to  it  the  power  of  affording  food  to  a 
new  crop,  or,  in  other  words,  we  reinstate  the  equilibrium  which 
had  been  disturbed.  Now  that  we  know  that  the  constituents  of 
the  food  pass  over  into  the  urine  and  excrements  of  the  animal 
fe(}  upon  it,  we  can  with  great  ease  determine  the  different  value 
of  various  kinds  of  manure.     The  solid  a.nd  liquid  excrements 

OF  AN  animal  are  OF  THE  HIGHEST  VALUP.  AS  MANURE  FOR  THOSE 
PLANTS   WHICH   FURNISHED    FOOD    TO    THE    ANIMAL.       The  duDg  of 

pigs  fed  upon  peas  and  potatoes,  is  in  the  highest  degree  adapted 
as  a  manure  for  fields  growing  peas  and  potatoes.     We  feed  a 


1000  parts  of 
Urine. 

|0(K)  parts  of 
the  residue 

Phosphate  of  swla           .         -         - 
"            ammonia  -         -         - 

-  2-94 

-  ]  -65 

4-39 
2-46 

Chloride  of  sodiui^i        -         -         - 

-       4-45 

6-64 

Muriate  of  ammonia      -         ,         . 

-       1-50 

2-23 

Phosphates  of  magnesia  and  Hme  - 
Silica    -        -,       - 

-  1-00 

-  0-03 

1-49 
005 

Water 

-  933-00 

10000 

1000-00 

1000  parts  of  hunaTi  faeces  yielded  150  f  • 

irti.  of  asiies, 

which  consisted 

of— (Berzelius)  : — 

Phosphate  of  lirrie 

■     -  ? 

"               magnesia 
Traces  of  gypsum 
Sulphate  of  siwli 

'*             j)otash 
Phosphate  of  soda 
Carbonate  of  soda 
Silica           .... 
Carbonaceous  lesid'.ie  and  loss 

:    :  \ 

100 

8 

8 
16 

18 

150 


174  ON  MANURE. 


cow  upon  hay  and  turnips,  and  we  obtain  a  manure  containing 
all  the  mineral  constituents  of  grass  and  of  turnips  ;  this  manure 
ought  to  be  preferred,  as  being  more  suitable  for  turnips  than 
that  procured  from  any  other  source.  The  dung  of  pigeons  con- 
tains the  mineral  ingredient  of  the  cereal  grains  ;  that  of  the 
rabbit,  the  constituents  of  culinary  vegetables ;  the  liquid  and 
solid  excrements  of  man  contain  in  very  great  quantity  the 
mineral  substances  of  all  seeds. 

According  to  the  above  view,  a  knowledge  of  the  constituents 
of  the  ashes  of  food  and  of  fodder,  gives  us  an  exact  indication 
of  the  ingredients  of  the  soil  contained  in  the  liquid  and  solid  ex- 
crements of  men  and  of  animals. 

If  we  know  the  quantity  of  the  food,  and  the  composition  of  its 
ashes,  we  know  also  with  certainty  how  much  soluble  salts  will 
be  contained  in  the  urine,  and  how  much  of  the  insoluble  salts 
will  exist  in  the  ffeces.  It  would,  therefore,  be  superfluous  and 
useless  to  state  Jiere  a  greater  number  of  analyses  of  excrements, 
because  these  analyses  must  differ  from  each  other,  quite  as 
much  as  tlic  variation  in  composition  of  the  ashes  of  the  food  on 
which  the  animal  was  fed. 

Common  stable  manure  is  a  mixture  of  j^olid  excrements  with 
urine,  which  gradually  enters  into  putrefaction  in  the  dunghill. 
In  consequence  of  the  putrefliclion  of  the  urine,  all  the  urea  con- 
tained in  it  is  converted  into  volatile  cy.rbonate  of  ammonia.  A 
large  portion  of  the  organic  ingredients  of  the  manure  enter  into 
decay  and  assume  a  gaseous  condition,  by  the  action  of  the  air, 
with  the  continued  evolution  of  heat.  The  weight  of  these 
ingredients  diminishes,  while  the  relative  proportion  of  the  fixed 
mineral  substances  increases.  if  all  the  d«:;caying  matters 
entered  into  union  with  oxygen,  the  result  of  course  would  be, 
that  those  not  susceptible  of  decay,  or,  in  otlier  words,  the  ashes, 
would  alone  reniain  behind.  Ti)e  following  analysis  will  illus. 
irate  the  meaning  of  tiiis  remark  : — 

100  })art.s  fresh  Cow-dung — 

Water  .         .         1         .         .         .     S5-900 

Combustible  substances        -     12* 


Ashes  •—     ''-''' 


2-352  > 
1-74S5 


100000 


MANURE  LOSES  ORGANIC  MATTER  BY  AGE. 


100  parts  Stable  Manure;  i  year  old.* 
Welter    -        -        -        -        -        -        -     79-3 

Coi'ibas*ible  substances           -       14'04 ) 
Ashes 6  66  5 


20-7 
100.0 


Now  that  we  k'''Ort  t'lnt  the  proportion  of  the  mineral  food  of 
plants  increases  with  tlie  age  of  the  dung,  that  old  dung  may 
contain  4  to  6  times  more  of  it  than  fresh  dung,  an  explanation  is 
furnished  of  the  relatively  greater  action  of  the  former,  and  of 
the  preference  accorded  to  it  by  farmers  of  experience. 

It  has  been  mentioned  in  the  preceding  part  of  the  chapter, 
that  animal  excrements  may  be  replaced  in  agriculture,  by  other 
materials  containing  their  constituents.  Now,  as  the  principal 
action  of  the  former  depends  upon  their  amount  of  mineral  food 
so  necessary  for  the  growth  of  cultivated  plants,  it  follows,  that 
we  might  manure  with  the  mineral  food  of  wild  plants,  or  in 
other  words,  with  their  ashes  ;  for  these  plants  are  governed 
by  the  same  laws,  in  their  nutrition  and  growth,  as  cultivated 
plants  themselves.  Thus,  these  ashes  might  be  substituted  for 
animal  excrements  ;  and  if  a  proper  selection  were  made  of  them, 
we  might  again  furnish  our  fields  with  all  the  constituent.** 
removed  from  them  by  crops  of  cultivated  plants.  The  vast  im- 
portance of  ashes  as  a  manure  is  recognised  by  many  farmers. 
In  the  vicinity  of  Marburg,  and  in  the  Wetterau,  such  a  high 
value  is  attached  to  this  costly  naterial,  as  a  manure,  that  the 
farmers  do  not  object  to  send  foi  t  to  a  distance  of  18  or  24  miles. 
The  importance  of  this  manure  will  be  more  obvious,  when  it  is 
considered,  that  wood-ashes  lixiviated  with  cold  water  contain 
silicate  of  potash,  in  exactly  the  same  proportion  as  straw 
(10  Si  O3,  +  KO) ;  and  that,  in  addition  to  this  salt,  it  contains 
considerable  quantities  of  phosp'iytcs. 

Different  kinds  of  wood-ashes  ])ossess  very  unequal  value  as 
manure.  Thus,  the  r.si.e.-s  of  the  oak  are  of  the  smallest,  those 
of  the  beech  of  t'jc  j^-reatest  vi-ue.  Wood-ashes  from  oak  contain 
4  to  5  per  cent,  of  phcsphatfs  ;  those  from  the  beech  contain  the 
fifth  part  of  their  weight  of  these  salts.     The  quantity  of  phos. 

•  Annales  f]e  Chirnio  et  de  Physique,  iii.  Serie,  237. 


176  ON  MANURE. 


phates  in  the  ashes  of  firs  and  pines  amounts  to  from  9  to  15  per 
cent.  :  the  ashes  of  the  poplar  contain  16 J  per  cent.,  and  those 
of  the  hazel-nut  tree  12  per  cent.* 

With  every  hundred  pounds  of  lixiviated  ashes  of  the  beech, 
we  furnish  to  the  soil  as  much  phosphates  as  are  contained  in 
460  lbs.  of  fresh  human  excrements. 

According  to  the  analysis  of  Saussure,  100  parts  of  the  ashes 
of  grains  of  wheat  contain  32  parts  soluble  and  44-5  parts  inso- 
luble, or  altogether  76*5  parts  of  soluble  and  insoluble  phosphates. 
The  ashes  of  wheat-straw  contain  in  all  11*5  per  cent,  of  phos- 
phates. Thus  with  every  100  lbs.  of  the  ashes  of  beech,  we 
furnish  to  the  field  phosphoric  acid  sufficient  for  the  production 
of  4000  lbs.  of  straw  (calculating  its  ashes  at  4  per  cent.,  accord- 
ing to  Saussure),  or  for  2000  lbs.  of  the  grains  of  wheat  (calcu-f 
lating  their  ashes  at  1-3  per  cent. — Saussure). 

The  dry  fruit  of  the  horse-chestnut  {JEsculus  hippocastanum) 
yields  34  per  cent,  of  ashes,  possessing  a  similar  composition  to 
the  ashes  of  maize,  and  of  the  grain  of  certain  kinds  of  wheat. f 

The  importance  of  manuring  with  bones  must  be  obvious  to 
all.  The  bones  of  man,  and  of  animals  in  general,  have  their 
origin  from  apatite  (phosphate  of  limo),  which  is  never  absent 
from  fertile  land.  The  bone  earth  passes  from  the  soil  into  hay, 
straw,  and  other  kinds  of  food,  which  are  afterwards  consumed 
by  animals.  Now,  when  we  consider  that  bones  contain  55  per 
cent,  of  the  phosphates  of  lime  and  magnesia  (Berzelius),  and  if 
we  assume  that  hay  contains  the  same  quantity  of  these  salts  as 

•  Ashes  of  pines  from  Norway  contain  the  jiiininmm  of  phosphates — 
viz.  0*9  per  cent. — Berthier. 

t  Ashes  of  the  fruit  of  the  horse-chestnut  [Saussurk]: 

Potash 51 

Alkaline  phosphate?     -         .         -         -  28 

Chloride  of  potasni'^rr.  x:A  sulphate  ^^       ^        o 

potash         -  -         -         -    5 

Earthy  phosphates         ....  12 

Silica 05 

Metallic  oxides  -        -        -        -        -025 

Loss  .....  ,  5.25 


10000 


BONE  MANURE.  17T 


wheat-straw,  then  it  follows  that  8  lbs.  of  bones  contain  as  much 
phosphate  of  lime  as  1000  lbs.  of  hay  or  of  wheat-straw,  and  20 
lbs.  as  much  phosphoric  acid  as  1000  lbs.  of  the  grain  of  wheat 
or  of  oats.  These  numbers  are  not  absolutely  correct,  but  they 
give  a  very  fair  approximation  of  the  quantity  of  phosphates 
yielded  annually  by  a  soil  to  these  plants.  By  manuring  an  acre 
of  land  with  60  lbs.  of  fresh  bones,  we  furnish  sufficient  manure 
to  supply  three  crops  (mangel-wurzel,  wheat,  and  rye)  with 
phosphates.  But  the  form  in  which  they  are  restored  to  a  soil 
does  not  appear  to  be  a  matter  of  indifference.  For  the  more 
finely  the  bones  are  reduced  to  powder,  and  the  more  intimately 
they  are  mixed  with  the  soil,  the  more  easily  are  they  assimi- 
lated. The  most  easy  and  practical  method  of  effecting  their 
division  is  to  pour  over  the  bones,  in  a  state  of  fine  powder,  half 
their  weight  of  sulphuric  acid  diluted  with  three  or  four  parts  of 
water,  and  after  they  have  been  digested  for  some  time,  to  add 
about  one  hundred  parts  of  water,  and  to  sprinkle  this  acid  mix- 
ture (phosphates  of  lime  and  magnesia)  before  the  plough.  In  a 
few  seconds,  the  free  acids  unite  with  the  bases  contained  in  the 
earth,  and  a  neutral  salt  is  formed  in  a  state  of  very  fine  division. 
Experiments  instituted  on  a  soil  formed  from  grauwacke,  for  the 
purpose  of  ascertaining  the  action  of  the  manure  thus  prepared, 
have  distinctly  shown  that  neither  corn  nor  kitchen-garden  plants 
suffer  injurious  effects  in  consequence  ;  but  that,  on  the  contrary, 
they  thrive  with  much  more  vigor.* 

In  the  manufactories  of  glue,  many  hundred  tons  of  a  solution 
of  phosphates  in  muriatic  acid  are  yearly  thrown  away  as  be 
ing  useless.  It  would  be  important  to  ascertain  how  far  this 
solution  might  be  substituted  for  bones.     The  free  acid  would 

*  Very  favorable  results  have  been  obtained  by  treating  seeds  in  the  fol 
lowing  manner: — The  seeds  about  to  be  sown  were  steeped  in  the  water 
from  a  dunghill,  and  while  still  wet,  were  strewed  with  a  mixture  of  20 
parts  of  fine  bone-dust  and  1  part  of  burnt  gypsum,  in  such  a  manner  that 
each  grain  was  covered  with  a  thin  layer  of  the  powder ;  by  sprinkling 
them  with  water  and  repeating  this  treatment  with  the  mixture,  the  coat- 
ing can  be  increased.  The  seeds  were  allowed  to  dry  in  the  air,  and  were 
then  sown  in  the  usual  way.  On  the  brge  scale  this  mode  of  dunging 
owing  to  its  being  rather  troublesome,  might  not  answer  the  purj)ose  M 
well  as  a  heavy  manuring  with  bones  and  gvpsum. 
9-^ 


17S  ON  MANURE 


combine  with  the  alkalies  in  the  soil,  especially  with  lime,  and  a 
soluble  salt  would  thus  be  produced,  which  is  known  to  possess  a 
favorable  action  on  the  growth  of  plants.  This  salt  (muriate  of 
lime,  or  chloride  of  calcium)  is  one  of  those  compounds  which 
attract  water  from  the  atmosphere  with  great  avidity,  and  retain 
it  when  absorbed  ;  and  being  present  in  the  soil,  it  would  decom- 
pose the  carbonate  of  ammonia  existing  in  rain-water,  with  the 
formation  of  sal-ammoniac  and  carbonate  of  lime.  A  solution 
of  bones  in  muriatic  acid  placed  on  land  in  autumn  or  in  winter, 
would  therefore  not  only  restore  a  necessary  constituent  of  the 
soil,  but  would  also  give  to  it  the  power  of  retaining  all  the  am- 
monia falling  upon  it  in  the  rain  for  a  period  of  six  months. 

The  ashes  of  brown  coal  and  of  peat  contain  frequently  silicate 
of  potash,  so  that  these  might  furnish  to  the  straw  of  the  cereals 
one  of  its  principal  constituents;  these  ashes  contain  also' 
phosphates. 

ft  is  of  much  importance  to  the  agriculturist,  that  he  should 
not  deceive  himself  respecting  the  causes  which  give  the  peculiar 
action  to  the  substances  just  mentioned.  It  is  known  that  they 
possess  a  favorable  action  on  vegetation ;  and  it  is  likewise  cer- 
tain, that  the  cause  of  this  is  their  containing  a  body,  which,  inde- 
pendently of  the  influence  exerted  by  its  physical  properties  of 
porosity  and  capability  of  attracting  and  retaining  moisture,  as- 
sists also  in  maintaining  the  vital  processes  of  plants.  But  if  the 
subject  be  treated  as  an  unfathomable  mystery,  the  nature  of 
their  influence  will  never  be  known. 

In  medicine,  for  many  centuries,  the  mode  of  action  of  all  reme- 
dies was  supposed  to  be  concealed  by  the  mystic  veil  of  Isis ; 
but  now  these  secrets  have  been  explained  in  a  very  simple  man- 
ner. An  unpoetical  hand  has  pointed  out  the  cause  of  the  won- 
derful and  apparently  inexplicable  healing  virtues  of  the  springs 
in  Savoy,  by  which  the  inhabitants  cured  their  goitre  :  the  water 
was  found  to  contain  small  quantities  of  iodine.  In  burnt  sponges 
used  for  the  same  purpose,  the  same  clement  was  also  detected. 
The  extraordinary  efficacy  of  Peruvian  bark  was  found  to  depend 
on  a  small  quantity  of  a  crj'stalline  body  existing  in  it,  viz. 
<^uinine ;  and  the  causes  of  the  various  effects  of  opium  were 
detected  in  as  many  different  ingredients  of  that  drug. 


CAUSES  OF  ACTION  SHOULD  BE  ASCERTAINED.    tW 

Now  all  such  actions  depend  on  a  definite  cause,  by  ascertain' 
ing  which,  we  place  the  actions  themselves  at  our  command. 

It  must  be  admitted  as  a  principle  of  agriculture,  that  those 
substances  which  have  been  removed  from  a  soil  must  be  com- 
pletely restored  to  it ;  but  whether  this  restoration  be  effected  bv 
means  of  excrements,  ashes,  or  bones,  is  in  a  great  measure  d 
matter  of  indifference.  A  time  will  come,  when  plants  growing 
upon  a  field  will  be  supplied  with  their  appropriate  manures  pre 
pared  in  chemical  manufactories — when  a  plant  will  rec(;ive  only 
sucl)  substances  as  actually  serve  it  for  food,  just  as  at  presen*  a 
few  grains  of  quinine  are  given  to  a  patient  afflicted  with  fever, 
instead  of  the  ounce  of  wood  which  he  was  formerly  compelled 
to  swallow  in  addition. 

There  are  some  plants  which  require  humus  (as  a  source  of 
carbonic  acid),  without  re-producing  it  in  any  appreciable  quantity ; 
whilst  others  can  do  without  it  altogether,  and  actually  enrich  a 
soil  deficient  in  it.  Hence  a  rational  system  of  agriculture  would 
employ  all  the  humus  at  command  for  the  supply  of  the  former 
and  not  expend  any  of  it  for  the  latter;  but  would  in  fact  make 
use  of  them  for  supplying  the  others  with  humus. 

We  may  furnish  a  plant  with  carbonic  acid,  and  with  all  the 
materials  which  it  may  require ;  we  may  supply  it  with  humus 
in  the  most  abundant  quantity  ;  but  it  will  not  attain  complete 
development,  unless  nitrogen  is  also  afforded  to  it ;  a  herb  will 
be  formed,  but  no  grain  ;  even  sugar  and  starch  may  be  produced, 
but  no  gluten. 

But,  on  the  other  hand,  the  supply  of  nitrogen,  in  the  form  of 
ammonia,  will  not  suflice  for  the  purposes  of  agriculture.  Al 
though  ammonia  is  of  the  utmost  importance  for  the  vigorous 
growth  of  plants,  it  is  not  in  itseif  sufficient  for  the  production  of 
vegetable  casein,  fibrin,  or  albumen.  These  substances  are  not 
known  in  a  free  state  ;  for  they  are  always  accompanied  by  alka* 
lies,  sulphates,  and  phosphates.  We  must  therefore  assume,  that 
without  their  co-operation,  ammonia  could  not  exercise  the  slight- 
est influence  on  the  growth  and  formation  of  the  seeds  ;  that,  ih 
such  a  case,  it  is  a  matter  of  perfect  imlifference  whether  ani- 
monia  is  conveyed  to  them  or  not ;  for  it  will  not  assist  in  the 
formation  of  the  constituents  of  the  blood,  unless  tlie  other  oondif^ 


ISO  JN  MANURE 


tions  necessary  for  their  production  be  present  at  the  same 
time. 

All  these  conditi.i:s  are  united  in  liquid  and  solid  excrements; 
none  of  them  are  absent.  In  these  are  present,  not  only  ammo- 
nia, but  also  alicalios,  phosphates,  and  sulphates,  in  the  relative 
pre    ition  in  which  they  exist  in  our  cultivated  plants. 

The  pDwerful  action  -f  urine  depends,  therefore,  not  only  on 
Its  compounds  of  nitr "^gen  ;  for  the  phosphates  and  sulphates  ac- 
companying these  take  a  ^ecidod  part  in  the  action. 

Urine,  in  the  state  in  which  it  is  used  as  manure,  does  not  con- 
tain urea,  as  this  substance  has  been  converted  into  carbonate  of 
ammonia  during  putrefaction.  In  dung  reservoirs,  well  con- 
structed and  protected  from  evaporation,  the  carbonate  of  ammo- 
nia Is  retained  in  solution.  When  the  putrefied  urine  is  spread 
over  the  land,  part  of  its  carbonate  of  ammonia  evaporates  along 
with  the  water,  while  another  portion  is  absorbed  by  the  soil,  par- 
ticularly  if  it  be  clayey  and  ferruginous  land;  but,  in  general, 
only  the  phosphate  and  muriate  of  ammonia  remain  in  the  ground. 
The  amount  of  the  latter  alone  enabJes  the  soil  to  exercise  a 
direct  influence  on  the  plants  during  the  progress  of  their  growth  ; 
and  as  they  are  not  volatile,  not  a  particle  of  them  escapes  being 
absorbed  by  the  roots. 

The  existence  of  carbonate  of  ammonia  in  putrefied  urine  long 
since  suggested  the  manufacture  of  sal-ammoniac  from  this  ma- 
terial. When  the  latter  salt  possessed  a  high  price,  this  manu- 
facture was  carried  on  by  the  farmer  himself.  For  this  purpose 
the  liquid  obtained  from  dunghills  was  placed  in  vessels  of  iron 
and  subjected  to  distillation  ;  the  product  of  this  distillation  was 
then  converted  into  muriate  of  ammonia  by  the  ordinary  methods 
(Demachy). 

The  carbonate  of  ammonia  formed  .  y  the  putrefaction  of  urine 
can  be  fixcv^,  or  be  deprived  of  its  volatility,  in  many  ways. 
When  a  field  is  strewed  with  gypsum,  and  then  with  putrefied 
urine,  or  with  the  drainings  of  dunghills,  all  the  carbonate  of 
ammonia  is  converted  into  the  sulphate,  which  remains  in  the 
soil. 

But  there  are  still  simpler  means  of  effecting  this  purpose : 
gypsum,  chloride  of  calcium,  sulphuric  or  muriatic  acid,  and 


CARBONATE  OF  AMMOxViA  IN  L.?*NF.  181 

superphosphate  of  lime,  are  substances  of  a  very  low  price  ;  and 
if  they  were  added  to  urine  until  the  latter  lost  its  alkalinity,  the 
ammonia  would  be  converted  into  salts,  which  would  have  r.o 
further  tendency  to  volatilize. 

When  a  basin,  filled  with  concentrated  muriatic  acid,  is  placed 
in  a  common  necessary,  so  that  its  surface  is  in  free  communica- 
tion with  the  vapors  issuing  from  below,  it  becomes  filled  after  a 
few  days  with  crystals  of  muriate  of  ammonia.  The  ammonia, 
the  presence  of  which  the  organs  of  smell  amply  testify,  combines 
with  the  muriatic  acid  and  loses  entirely  its  volatility,  and  thick 
clouds  or  fumes  of  the  salt  newly-formed  hang  over  the  basin.  In 
stables,  the  same  may  be  seen.  The  ammonia  escaping  in  this 
manner  is  not  only  lost,  as  far  as  our  vegetation  is  concerned,  but 
it  works  also  a  slow,  though  not  less  certain,  destruction  of  the 
walls  of  the  building.  For,  when  in  contact  with  the  lime  of  the 
mortar,  it  is  converted  into  nitric  acid,  which  dissolves  gradually 
the  lime.  The  injury  thus  done  to  a  building  by  the  formaticr 
of  soluble  nitrates,  has  received  (in  Germany)  a  special  name  • 
salpeterfrass  (production  of  soluble  nitrate  of  lime). 

The  ammonia  emitted  from  stables  and  necessaries  is  always 
in  combination  with  carbonic  acid.  Carbonate  of  ammonia  and 
sulphate  of  lime  (gypsum)  cannot  be  brought  together  at  common 
temperatures,  without  mutual  decomposition.  The  ammcnia 
enters  into  combination  with  the  sulphuric  acid,  and  the  carbonic 
acid  with  the  lime,  forming  compounds  destitute  of  volatility,  and 
consequently  of  smell.  Now,  if  we  strew  the  floors  of  our  stables, 
from  time  to  time,  with  common  gypsum,  they  will  lose  all  their 
ofFensive  smell,  and  none  of  the  ammonia  can  be  lost,  but  will  be 
retained  in  q,  condition  serviceable  as  manure  (Mohr). 

With  the  exception  of  urea,  uric  acid  contains  more  nitrogen 
than  any  other  substance  generated  by  the  living  organism  ;  it  is 
soluble  in  water,  and  can  be  thus  absorbed  by  the  roots  of  plants, 
and  its  nitrogen  will  be  assimilated  in  the  form  of  ammonia  from 
the  oxalate,  hydrocyanate,  or  carbonate  of  ammonia.  It  would 
be  extremely  interesting  to  study  the  transformations  which  uric 
acid  suffers  in  a  living  plant.  For  the  purpose  of  experiment, 
the  plant  should  be  made  to  grow  in  charcoal  powder. previously 
heated  to  redness,  and  then  mixed  with  pure  uric  acid.     The  ex- 


ON  MANURE. 


aminatioii  cf  the  juice  of  the  plant,  or  of  the  component  parts  of 
the  seed  or  fruit,  would  be  an  easy  means  of  detecting  the 
differences. 

In  respect  to  the  quantity  of  nitrogen  contained  in  excrements, 
iOO  parts  of  the  urine  of  a  healthy  man  are  equal  to  1300  parts 
«4)f  the  fresh  dung  of  a  horse,  according  to  the  analysis  of  Macaire 
and  Marcet,  and  to  600  parts  of  the  fresh  dung  of  a  cow. 
The  powerful  effects  of  urine  as  a  manure  are  well  known  in 
Flanders,  and  they  are  considered  invaluable  by  the  Chinese,  who 
are  the  oldest  agricultural  people  we  know.  Indeed,  so  much 
alue  IS  attached  to  the  influence  of  human  excrements  by  these 
'oeople,  that  laws  of  the  state  forbid  that  any  of  these  excrements 
should  be  thrown  away,  and  reservoirs  are  placed  in  every  house, 
m  which  they  are  collected  with  the  greatest  care.  No  other 
kind  cf  manure  is  used  for  their  corn-fields. 

On  the  assumption,  that  the  liquid  and  solid  excrements  of  man 
amount,  on  an  average,  to  only  1^  lb.  daily  (^  lb.  of  urine  and 
J  lb.  faeces),  and  that  both  taken  together  contain  3  per  cent,  of 
nitrogen,  then,  in  one  year,  they  will  amount  to  547  lbs.,  con- 
taining 16*41  lbs.  of  nitrogen,  a  quantity  sufficient  to  yield  the 
nitrogen  of  800  lbs.  of  wheat,  rye,  oats,  or  of  900  lbs.  of  barley. 

(BOUSSINGAULT.') 

This  is  much  more  than  it  is  necessary  to  add  to  an  acre  of 
land,  in  order  to  obtain,  with  the  assistance  of  the  nitrogen  ab- 
sorbed from  the  atmosphere,  the  richest  crops  every  year.  By 
adopting  a  system  of  rotation  of  crops,  every  town  and  farm  might 
thus  supply  itself  with  the  manure,  which,  besides  containing 
the  most  nitrogen,  contains  also  the  most  phosphates.  By  using, 
at  the  same  time,  bones  and  the  lixiviated  ashes  of  wood,  animal 
excrements  might  be  completely  dispensed  with  on  many  kinds 
of  soil. 

When  human  excrements  are  treated  in  a  proper  manner,  so  as 
to  remove  this  moisture,  without  permitting  the  escape  of  am- 
monia, they  may  be  put  into  such  a  form  as  will  allow  them  to  be 
transported  even  to  great  distances. 

This  is  already  attempted  in  many  towns,  and  the  preparation 
of  nigiit-soil  for  transportation  constitutes  not  an  unimportant 
branch  of  industry. 


NITROGEN  IN  EXCREMENTS,  183 


In  Paris,  for  example,  the  excrements  arc  preserved  in  tho 
houses  in  open  casks,  from  which  they  are  collected  and  placed 
in  deep  pits  at  Montfauqon,  but  they  are  not  sold  until  they  have 
attained  a  certain  degree  of  dryness,  by  evaporation  in  the  air. 
But  whilst  lying  in  the  receptacles  appropriated  for  them  in  the 
houses,  all  their  urea  is  converted  for  the  most  part  into  carbonate 
of  ammonia  :  the  vegetable  matter  contained  in  them  putrefies, 
all  the  sulphates  are  decomposed,  and  the  sulphur  forms  sul- 
phuretted hydrogen  (volatile  hydrosulphate  of  ammonia).  The 
mass,  when  dried  by  exposure  to  the  air,  has  lost  the  greatest  part 
of  its  nitrogen  along  with  its  water,  and  llie  residue,  besides  phos- 
phate of  annnonia,  consists  for  the  most  p.irt  of  phosphate  of  lime 
and  magnesia,  together  with  fatty  matters.  Tins  manure  is  sold 
in  France  under  the  name  of  FoudreltSf  and  is  very  highly  esti- 
mated, on  account  of  its  powerful  action.  TJiis  action  cannot 
depend  on  the  ammovj'r.  originally  contained  in  it,  because  the 
greatest  part  has  escaped  daring  the  desiccation.  According  to 
the  analyses  of  Jaquemars,  the  I'arisian  poutlrolle  does  not  con- 
tain more  than  1'8  per  cent,  of  annnonia. 

In  other  manufactories  of  manure,  the  night-soil,  whiht  still 
soft,  is  mixed  with  the  ashes  of  woo;l,  or  with  earth,  <&c.,  con- 
taining a  large  quantity  of  c?.ustic  linje,  and  this  causes  a  com- 
plete expulsion  of  all  the  ammonia  of  the  excrements,  depriving 
them  in  consequence  of  all  smell.  The  efficacy  of  this' manure 
cannot,  therefore,  depend  upon  its  nitrogen. 

It  is  evident  that,  if  we  place  the  solid  or  liquid  excrements  of 
man,  or  the  liquid  excrements  of  animals  on  our  land,  in  equal 
proportion  to  the  quantity  of  nitrogen  removed  from  it  in  the 
form  of  plants,  the  sum  of  this  element  in  ihe  soil  nnist  increase 
every  year;  for  to  the  quantity  which  we  thus  supply,  another 
portion  is  added  from  tho  atmosphere.  There  is  no  proper  loss 
of  nitrogen  to  plants,  for  even  the  small  quantity  of  this  elei.ient 
which  man  carries  with  him  to  the  grave  is  not  finally  lost  to 
vegetation,  for  it  escapes  into  the  earth,  and  into  the  atmosphere, 
as  ammonia,  during  the  decay  and  putrefaction  of  the  body. 

A  high  degree  of  culture  requires  an  increased  supply  of  ma- 
nure. With  the  abundance  of  the  manure  the  produce  in  corn  and 
cattle  will  augment,  but  must  diminish  with  its  deficiency. 


I8i  ON  MANURE. 


The  substances  applicable  as  manure  ought  to  be  arranged 
according  to  the  products  desired.  Tile  alkalies  are  peculiarly 
necessary  for  the  production  of  vegetable  constituents  destitute 
of  nitrogen,  such  as  sugar,  starch,  pectin,  and  gum  ;  phosphates 
are  peculiarly  valuable  for  the  formation  of  the  constituents  of 
the  blood.  A  field  richlv  treated  with  animal  manure,  and 
therefore  with  phosphates,  producea  a  barley  which  is  rejected 
by  the  brewer  of  beer,  because  it  is  too  rich  in  the  constituents 
of  the  blood,  and  proportionally  poor  in  starch.  Hence,  the 
very  ingredient  which  is  of  the  highest  value  to  the  feeders  of 
stock,  is  held  in  low  estimation  by  the  brewer ;  because  the 
object  of  the  first  is  to  produce  flesh,  the  object  of  the  latter  is 
the  fabrication  of  alcohol. 

Frefsli  bones,  wool,  hair,  rags,  hoofs,  and  horn,  are  manures 
containing  nitrogen  as  well  as  pliosphates,  and  are  consequently 
fit  to  aid  the  process  of  vegetable  life. 

One  hundred  parts  of  dry  bones  contain  from  32  to  33  per 
cent,  of  dry  gelatine  ;  now,  supposing  this  to  contain  the  same 
quantity  of  nitrogen  as  aniraal  glue — viz.  5*28  per  cent.,  then 
100  parts  of  bones  must  be  considered  as  equivalent  to  250  parts 
of  human  urine. 

Bones  may  be  preserved  for  thousands  of  years,  in  dry,  or 
even  in  moist  soils,  provided  the  access  of  air  is  prevented  ;  as  is 
exemplified  by  the  bones  of  antediluvian  animals  found  in  loam 
or  gypsum,  the  interior  parts  being  protected  by  the  exterior 
from  the  action  of  water.  But  they  become  warm  when  reduced 
to  a  fine  powder,  and  moistened  bones  generate  heat  and  enter 
into  putrefaction  ;  the  gelatine  is  decomposed,  and  its  nitrogen 
is  converted  into  carbonate  of  ammonia  and  other  ammoniacal 
salts,  which  are  retained  in  a  great  measure  by  the  powder 
itself.* 

Charcoal,  in  a  state  of  powder,  must  be  considered  as  a  very 
powerful  means  of  promoting  the  growth  of  plants  on  heavy 
soils,  and  particularly  on  such  as  consist  of  argillaceous  earth. 

Ingenhouss  proposed  dilute  sulphuric  acid  as  a  means  of  in- 


*  Boneit  burnt  till  quite  white,  and  recently  heated  to  redness,  absorb 
7*5  times  their  volume  of  pure  ammoniacal  gas. 


BONE  MANURE.  IM 


creasing  the  fertility  of  a  soil.  Now,  when  this  acid  is  sprinkled 
on  calcareous  soils,  gypsum  (sulphate  of  lime)  is  immediately 
formed,  which,  of  course,  prevents  the  necessity  of  manuring  the 
ground  with  this  material.  100  parts  of  concentrated  sulphuric 
acid  diluted  with  from  800  to  1000  parts  of  water,  are  equiva- 
lent to  176  parts  of  gypsum. 

Many  kinds  of  ashes,  of  peat,  and  most  varieties  of  coal 
ashes,  contain  an  abundant  quantity  of  gypsum,  by  which  they 
exercise  a  very  favorable  influence  on  certain  soils. 


Ashes  f>f  iMjfit 

Ashes  of  peat 

from  Fichtelgebirge. 

from  Bassy  (Dep.  de  la  Mnni*> 

FlKKKTSCHKR 

Bkrthikr. 

Silica       -         -         -     36  0^ 

Alumina           -         -     17-3  >      - 

-     22-5 

Peroxide  of  iron       -     330  ) 

Carbonate  of  lime    -       20  )      _ 
Magnesia         -         -       35 )      '  *     ' 

-     .^1-5 

Gypsum  -        -         -       4'5        -        - 

-    360 

Chloride  of  calcium        0-5 

Carbonaceous  residue    2'7 

t8«  RETROSPECT. 


CHAPTER    XIII. 

Retrospective  View  of  the  Preceding  Theories. 

The  knowledge  of  the  processes  of  nutrition,  in  the  case  of  the 
culture  of  meadow  and  of  forest  land,  indicates  that  the  atmo- 
sphere  contains  an  inexhaustible  quantity  of  carbonic  acid. 

On  equal  surfaces  of  wood  or  of  meadow  land,  in  which  exist 
the  constituents  of  the  soil  indispensable  to  vegetation,  we  obtain 
crops  without  the  application  of  carbonaceous  manures  ;  ancl 
these  crops  contain,  in  the  form  of  wood  and  hay,  a  quantity  of 
carbon  equal  to,  or,  in  many  cases,  greater  than  that  produced 
by  cultivated  land  in  the  form  of  straw,  corn,  and  roots. 

It  is  obvious  that  the  cultivated  land  must  have  presented  to  it 
as  much  carbonic  acid  as  is  furnished  to  an  equal  surface  of 
wood  or  of  meadow  land  ;  that  the  carbon  of  this  carbonic  acid 
becomes  assimilated,  or  is  capable  of  assimilation,  if  the  con- 
ditions exist  for  its  reception  and  conrersion  into  a  constituent 
of  plants. 

However  great  may  be  the  supply  of  food  in  a  soil,  it  will  be 
sterile  for  most  plants,  if  water  be  deficient.  At  certain  seasons 
of  the  year  rain  fructifies  our  fields;  seeds  neither  germinate 
nor  grow  without  a  certain  quantity  of  moisture. 

The  action  of  rain  is  much  more  striking  and  wonderful  to  the 
superficial  observer  than  that  of  manure.  For  weeks  and 
months,  the  influence  wiiich  it  exerts  on  the  crops  is  appreciable, 
and  yet  very  small  quantities  of  carbonic  acid  and  ammonia  are 
introduced  to  the  soil  by  means  of  rain. 

Water  plays,  doubtless,  a  decided  part  in  the  growth  of  plants, 
by  virtue  of  its  elements  ;  but,  at  the  same  time,  it  is  a  mediating 
member  of  all  organic  life.  Plants  receive  from  the  soil,  by  the 
aid  of  water,  the  alkalies,  alkaline  earths  and  phosphates  neces- 
sary to   the    formation  of  thsir   organs.      If  these   substances, 


CARBONIC  ACID  FURNISHED  BY  HUMUS.  187 


which  are  necessary  for  the  passage  of  atmospheric  food  into  the 
organism  of  the  plant,  be  deficient,  its  growth  must  be  impeded. 
Its  proper  growth,  in  dry  seasons,  stands  in  exact  relation  to  the 
quantity  of  the  substances  taken  up  from  the  soil  during  the  first 
period  of  its  development.  But  on  a  soil  poor  in  mineral  food, 
cultivated  plants  do  not  flourish,  however  abundantly  water  may 
be  supplied  to  them. 

The  crop  of  a  meadow,  or  of  an  equal  surface  of  wood-land,  is 
quite  independent  of  carbonaceous  manures,  as  far  as  regards 
its  carbon  ;  it  is  dependent  on  the  presence  of  certain  ingredients 
of  the  soil  destitute  of  carbon,  and  also  on  the  conditions  which 
enable  these  to  enter  into  the  plants.  Now,  we  are  able  to  in- 
crease the  crop  of  carbon  on  our  cultivated  lujid,  by  the  use  of 
burnt  lime,  ashes,  or  marl, — by  substances,  therefore,  which  are 
entirely  free  from  carbon.  This  well-ascertained  tact  indicates 
that  we  furnish  to  tiie  field,  in  these  substances,  certain  constitu- 
ents, which  enable  the  cultivated  plants  to  increase  in  mass,  and 
consequently  in  carbon — a  power  which  they  possessed  formerly 
only  in  a  small  degree. 

After  these  considerations,  it  cannot  be  denied  that  the  sterility 
of  a  field,  or  its  poverty  of  produce  in  carbon,  does  not  arise 
from  a  deficiency  of  carbonic  acid,  or  of  humus  ;  for  we  have 
seen  that  this  produce  can  be  increased,  to  a  certain  extent,  by 
the  supply  of  matters  destitute  of  carbon.  Rut  the"  very  same 
source  which  supplies  the  meadow  and  woodland  wilh  carbon, 
namely  the  atmosphere,  can  yield  that  element  to  cultivated 
plants.  It  therefore  becomes  especially  necessary  in  agriculture 
to  employ  the  best,  and  most  convenient  means,  of  enabling  the 
carbon  of  the  atmosphere  (carbonic  acid)  to  pass  over  into  the 
plants  growing  on  our  fields.  The  art  of  agriculture,  in  the 
mineral  food  which  it  supplies,  furnishes  to  plants  the  means  of 
appropriating  their  carbon  from  sources  offering  an  inexhaustible 
provision.  But  when  these  constituents  of  the  soil  are  wanting, 
the  most  abundant  supply  of  carbonic  acid,  or  of  decaying  vege- 
table matter,  cannot  increase  the  crop>s  on  the  field. 

The  quantity  of  carbonic  acid  that  can  pass  from  the  air  inio 
plants,  is  limited,  in  a  given  time,  by  the  quantity  of  carbonic 
acM  entering  into  contfict  with  the  org;uis  destined  for  its  absorp- 


188  RETROSPECT 


tion.  Now,  the  passage  of  carbonic  acid  from  the  air  into  the 
organisMi  of  the  plant  is  efTected  by  means  of  the  leaves ;  hut 
the  absorption  of  carbonic  acid  cannot  take  place  without  the 
contact  of  its  particles  with  the  surface  of  the  leaf,  or  of  a  part 
of  the  plant  capable  of  absorbing  it.  Hence,  in  a  given  timi 
the  quantity  of  carbonic  acid  absorbed  must  stand  in  exact  pro- 
portion to  the  surface  of  the  leaves,  and  to  the  amount  of  it  exist- 
ing in  the  air. 

Two  plants  of  the  same  kind,  with  equal  surfaces  of  leaves 
(i.  e.  surfaces  of  absorption),  will  take,  during  the  same  time,  and 
under  like  conditions,  t)ie  same  amount  of  carbon.  And  if  the 
air  contains  double  the  quantity  of  carbonic  .icid  tha*  it  does  at 
another  time,  the  plants,  under  like  conditions,  will  absorb  double 
the  quantity  of  carbon.*  A  plant  with  only  half  the  surfaces 
of  the  leaves  of  another  plant  will  absorb  quite  as  much  carl)on 
as  the  latter,  if  the  air  supplied  to  the  former  contains  twice  the 
amount  of  carbonic  acid. 

These  considerations  point  out  to  us  the  cause  of  the  favorable 
action  exerted  on  cultivated  plants  by  humus,  and  by  all  decaying 
organic  substances. 

Young  plants,  when  dependent  on  the  air  alone,  can  cnlv 
increase  their  amount  of  carbon  according  to  their  absorbing 
surfaces.  But  it  is  obvious,  if  their  roots  receive,  by  means  of 
Immus,  three  times  the  amount  ot  carbonic  acid  absorbed  by 
their  leaves  in  the  same  time,  their  increase  in  weight  will  bo 
fourfold,  on  the  assumption  of  the  existence  of  all  the  conditions 
for  the  assimilation  of  the  carbon.  Hence,  four  times  the  quan- 
tity of  stems,  leaves,  and  buds,  must  be  formed  ;  and,  by  the 
increased  surface  thus  obtained,  the  plants  will  receive  in  the 
same  degree  an  increased  power  of  absorbing  food  from  the  air ; 
and  this  power  remains  in  activity  long  after  the  supply  of  carbon 
to  the  roots  has  ceased. 

But  the  use  of  hunms  as  a  source  of  carbonic  acid,  in  arable 
land,  is  not  only  to  increase  the  amount  of  carbon  in  the  plant ; 

•  Boussingault  remarked  that  leaves  of  a  vine  inclosed  in  a  globe  re- 
moved completely  from  the  air  all  the  carbonic  acid  contained  in  it,  how- 
ever rapidly  the  stream  of  air  was  made  to  pass.  (Dumas:  Lecturei* 
p.  23.) 


UNEQUAL  PRODUCTION  OF  CONSTITUENTS.  18« 


for,  by  the  increased  size  attained  by  the  plant  in  a  given  time, 
there  is  also  given,  in  fact,  space  for  the  reception  of  the  consti- 
tuents of  the  soil  necessary  for  the  formation  of  new  leaves  and 
twigs. 

From  the  surface  of  young  plants  a  constant  evaporation  of 
water  takes  place,  the  amount  of  which  is  in  proportion  to  the 
temperature  and  surface.  The  numerous  fibres  of  the  roots 
supply  the  water  which  is  evaporated,  just  as  if  they  were  so 
many  pumps ;  so  that,  as  long  as  the  soil  continues  moist,  the 
plants  receive,  by  means  of  water,  the  necessary  constituents  of 
the  soil.  A  plant  with  double  the  surface  of  another  plant  must 
evaporate  twice  the  (juantity  of  water  that  the  latter  does.  The 
water  thus  absorbed  is  expelled  again  in  vapor,  but  the  salts  and 
constituents  of  the  soil  introduced  to  th(i  plant  by  its  agency, 
.still  remain  there.  A  plant  with  twice  the  surface  of  leaves  of 
another  plant,  but  with  the  same  quantity  of  water  in  proportion 
to  its  size,  still  receives  from  the  same  soil  a  greater  quantity 
of  ingredients,  in  proportion  to  its  water,  than  the  latter  plant 
receives. 

The  growth  of  the  latter  soon  reaches  a  termination  when  the 
further  supply  ceases,  while  the  former  continues  to  grow,  be- 
cause it  contains  a  larger  quaiitity  of  the  substances  necessary 
for  the  assimilation  of  atmospheric  food.  But  m  both  plants  the 
number  and  size  of  the  seeds  will  altogether  depend  upon  the 
amount  of  the  mineral  ingredients  of  the  seed  existing  in  the 
plants  ;  the  plants  containing  or  receiving  from  the  soil  a  greater 
amount  of  alkaline  and  earthy  phosphates  than  other  plants  obtain 
in  the  same  time,  will  also  produce  a  greater  number  of  seeds 
than  the  latter. 

Thus  it  is  that,  in  a  hot  summer,  when  the  supply  of  the  con- 
stituents of  the  soil  is  cut  off  by  rain,  the  height  and  strength  of 
the  plants,  and  the  development  of  the  seed,  stand  in  exact  pro- 
portion to  the  quantity  of  the  constituents  of  the  soil  taken  up 
during  their  former  period  of  growth. 

The  produce  of  a  field  in  corn  and  in  straw  varies  very  con- 
siderably in  different  years.  In  one  year  we  may  obtain  the 
same  weight  of  corn  of  similar  composition  to  that  obtained  in 
another  year,  but  the  crop  of  straw  may  be  considerably  greater ; 


YjjH,  -----     V       RETROSPECT. 


or  the  reverse  may  take  place,  and  the  crops  of  straw  (of  carbon) 
may  be  equal,  while  the  corn  may  amount  to  double  the  quantity. 
But  when  we  obtain  twice  the  quantity  of  corn  from  the  same 
surface,  we  must  have  also  a  corresponding  increase  of  the  con- 
stituents of  the  soil  in  the  corn  ;  or,  when  we  obtain  twice  the 
quantity  of  straw,  there  must  be  twice  the  amount  of  the  ingre- 
dients of  the  soil  in  llie  straw.  In  one  year  the  wheat  may  be 
3  feet  in  height,  and  yield  I2t0  lbs.  of  seed  per  acre,  while,  in 
another  year,  it  may  grow  one  foot  higher,  and  yet  yield  only 
800  lbs. 

An  unequal  crop  indicates,  under  all  circumstances,  an  une- 
qual proportion  of  the  constituoiils  of  the  soil  taken  up  for  the 
formation  of  the  corn  and  of  the  straw.  Straw  contains  and 
requires  phosphates,  as  well  as  corn,  but  in  much  smaller  pro- 
portion. 

In  a  wet  spring,  when  the  supply  of  these  salts  is  not  so  great 
as  that  of  n!k  -.iies,  of  silica,  and  of  sulphates,  the  crop  of  seeds 
becomes  diinihisinMl  ;  because  a  certain  quantity  of  the  phos- 
phates, which  woL\ld  otiu-rwise  be  employed  in  the  formation  of 
the  seeds,  is  now  used  for  the  production  of  the  stem  and  lea^ves ; 
the  constituents  of  the  seeds  cannot  be  perfected  without  an 
abundant  supply  of  phosphates.  By  depriving  a  plant  of  these 
salts,  we  could  produce  artificially  the  state  iu  which  they  attain 
a  height  of  three  feet,  and  blossom  without  ihe  production  of 
seeds.  The  crop  of  corn  growing  on  a  soil  rich  in  the  consti- 
tuents of  straw  (a  fat  soil),  is  often  less  in  a  wet  spring  than  upon 
a  soil  poor  in  these  ingredients  (a  thin  soil),  because  the  supply 
of  mineral  food  on  the  latter  is  greater  in  the  same  time,  and  is 
in  better  proportion  for  the  growth  of  all  the  constituents  of  plants 
than  in  the  former  case. 

On  the  supposition  that  all  the  conditions  necessary  to  our  cul- 
tivated plants,  for  the  assimilation  of  food  from  the  atmosphere, 
existed  in  the  most  favorable  form,  yet  the  action  of  humus  would 
be  useful  in  effecting  a  more  rapid  growth  of  the  plants,  and 
thus  GAINING  TIME,  ill  all  cases,  the  crop  of  carbon  is  increased 
by  means  of  humus ;  and  if  the  conditions  be  absent  for  the  eon- 
version  of  this  element  into  other  constituents,   it   a9<«M»ifMM»   the 


AMOUNT  OF  NITROGEN  IN  DIFFERENT  CROPS.        191 

form  of  starch,  gum,  and  of  sugar,  that  is,  of  substances  destv 
^llte  of  mineral  ingredients. 

Every  moment  of  time  is  of  value  in  the  practice  of  farming ; 
and,  in  this  respect,  humus  is  of  especial  importance  in  kitchen 
gardening. 

Our  corn  plants  and  edible  roots  find  in  our  fields,  in  the  form 
of  the  remains  of  a  past  vegetation,  sufficient  vegetable  matter  to 
correspond  to  the  mineral  food  existing  in  the  soil,  and,  therefore, 
with  sufficient  carbonic  acid  to  produce  a  quick  growth  during 
spring.  Any  further  supply  of  carbonic  acid  would  be  wholly 
useless,  unless  it  were  accompanied  by  a  corresponding  increase 
of  the  mineral  constituents  adapted  to  form  parts  of  the  plant. 
Upon  a  Hessian  acre  of  good  meadow  land  we  obtain  2500  lbs.  of 
hay,  according  to  the  opinion  of  experienced  farmers.  Meadows 
yield  this  crop,  without  any  suj>ply  of  organic  matters,  '•r  with- 
out any  manures  containing  nitrogen  or  carbon.  By  proper  irri- 
gation, and  by  treatment  with  ashes  and  gypsum,  the  crop  can 
be  increased  to  double  the  amount.  Let  us  assume,  however, 
that  the  2500  lbs.  of  hay  form  the  maximum  crop  ;  still,  it  is 
certain  that  all  the  carbon  and  nitrogen  of  the  plants  constituting 
it  must  have  been  obtained  from  the  air. 

According  to  Boussingault,  hay,  dried  at  tlie  temperature  of 
boiling  water,  contains  45*8  per  cent,  of  carbon  (a  result  agree- 
ing with  analyses  made  in  this  laboratory),  and  1"5  per  cent,  of 
nitrogen  ;  hay  dried  in  air  still  retains  14  per  cent,  of  water, 
which  escapes  at  the  heat  of  boiling  water. 

2500  lbs.  of  hay,  dried  in  air,  correspond  to  2150  lbs.  of  hay 
dried  at  the  temperature  of  boiling  water.  With  the  984  lbs.  of 
carbon  contained  in  the  crop  of  2150  lbs.  of  hay,  we  have  also 
removed  from  the  acre  of  meadow-land  32*2  lbs.  of  nitrogen. 
If  we  assume  that  this  nitrogen  has  entered  the  plant  in  the  form 
of  ammonia,  it  is  obvious  that  for  every  3640  lbs.  of  carbonic 
acid  (calculated  at  27  per  cent,  of  carbon)  the  air  contains  39*  1 
lb«.  ammonia  (taken  at  82  per  cent,  of  nitrogen) ;  or  that,  for 
every  1000  lbs.  of  carbonic  acid,  the  air  contains  IO-j^q-  lbs.,  am- 
monia— a  quantity  corresponding  to  about  -io-^oTo"  ^^  ^^^®  weight 
of  the  air,  or  of  -yo-Vo?  of  its  volume. 

Thus  fcr  every  100  parts  of  carbonic  acid  absorbea  by  tho 


IW  RETROSPECT 


surface  of  the  leaves  of  the  meadow  plants,  there  must  also  be 
absorbed  from  the  air  above  one  part  of  ammonia.  When  we 
calculate  how  much  nitrogen  different  plants  obtain  from  equal 
surfaces  of  land,  basing  our  calculations  r»n  known  analyses,  the 
following  results  are  obtained  : 


lbs.  of  carbon  remove 

in  nitrogen- 

- 

From 

meadow  land,  in  hay 

-  32-7 

" 

arable 

land, 

in  wheat 

- 

-  21-5 

u 

i< 

oats 

- 

-  22-3 

•< 

" 

rye     - 

- 

15-2 

•< 

•I 

potatoes 

- 

-  341 

" 

•♦ 

mangel-wurzel 

-  39-1 

" 

'* 

clover 

- 

-  44 

•< 

(t 

peas 

- 

-  62 

These  facts  lead  to  certain  conclusions  of  high  importance  to 
agriculture.  We  observe,  in  fact,  that  the  proportion  of  nitro- 
gen absorbed,  relatively  to  that  of  carbon,  stands  in  a  fixed  rela- 
tion to  the  surface  of  the  leaves. 

1.  Plants  containing  nearly  all  their  nitrogen  concen- 
trated IN  THEIR  SEEDS,  SUCH  AS  THE  CEREALS,  CONTAIN  ALTO- 
GETHER LESS  NITROGEN  THAN  THE  LEGUMINOUS  PLANTS,  PEAS  AND 
CLOVER. 

2.  The  crop  of  nitrogen  from  a   meadow   to   which   no 

AZOTIZED  manure  HAS  BEEN  GIVEN,  IS  MUCH  GREATER    THAN    THAT 
>R0M  a  MANURED  FIELD  OF  WHEAT. 

3.  The  crop  of  nitrogen  in  clover  or  in  peas  is  much 
greater  than  that  of  a  highly-manured  field  of  potatoes 
or  of  turnips. 

Boussingault  obtained  in  five  yeaEs,-from  his  farm  in  Bechel- 
bronn,  Alsace,  in  tlie  form  of  potatoes,  wheat,  clover,  turnips,  and 
oats,  8383  carbon,  and  250-7  nitrogen  ;  in  the  succeeding  five 
years,*  8192  carbon,  284-2  nitrogen  ;  in  a  third  rotation  of  six 
years,t  10949  carbon,  353"6  nitrogen  ;  or,  in  sixteen  years, 
27424  carbon,  and  858-5  nitrogen ;  or  altogether,  in  the  pro- 
portion  OF  1000  CARBON  to  31-3  NITROGEN. 

•  Beet,  wheat,  clover,  wheat,  late  turnips,  oats,  rye. 
t  Potatoes,  wl»eat,  clover,  wheat,  late  turnips,  peas,  rye. 


INOKGANIC  MANURE.  193 


A  most  remarkable  and  iinpo^rtant  result  follows  from  this  ex- 
periment — that  when  potatoes,  wheat,  turnips,  peas,  and  clover 
(roTASH,  LIME,  and  silica  plants),  are  cultivated  successively  on 
the  same  field,  altJKJUgh  this  field  had  been  thrice  manured  in  the 
course  of  sixteen  years,  the  »a»>e  relation  of  nitrogen  to  a  given 
quantity  of  carbon  is  obtainet),  ay  in  the  case  of  a  meadow  which 
had  received  no  manure. 

Carbon.  Nitrogen. 
Upon  an  acre  of  meadow  land  there  is  cropped  of  silica,  >       ^.q  .        ^q-.t 

lin>e,  and  potash  plants,  taken  together         -         -    ) 
On  an  acre  of  arable  land,  on  a  sixteen  years'  average,  of  )       ^-  -  „ 

silica,  lime,  and  potash  plants         -  '         -       }         '^ 

When  we  take  into  consideration  the  amount  of  carbon  and 
nitrogen  in  tlie  leaves  of  the  beet  and  potatoe  (for  the  leaves 
were  not  calculated  in  the  produce  of  the  arable  land),  then  it 
follows  that,  notwithstanding  all  the  supply  of  carbon  and  of  ni- 
trogen furnished  in  the  manure,  the  arable  land  lias  not  produced 
more  of  these  elements   than  an  ec^ual  surface  of  meadow  land, 

WHICH    RECEIVED  ONLY  MINERAL  FOOD  (cOllHtitUents  of  the  Soil). 

Then,  on  what  depends  the  peculiar  action  of  manures, 
and  of  the  liquid  and  solid  excrements  of  animals  ? 

This  question  is  susceptible  of  a  simple  solution.  Tliese 
manures  have  a  very  decided  action  on  our  arable  land,  from 
which  for  conturi(\s  we  hnve  removed,  in  the  form  of  cattle  and 
of  corn,  a  certain  quantity  of  oorivStituents  of  the  soil  which  have 
not  been  restored. 

If  no  manure  hud  been  applieu  to  the  land  during  the  sixteen 
years  of  tlic  above  experiTuent,  the  crop  would  have  mounted  to 
only  a  half  or  third  part  of  th?  carbaa  and  nitrogen. 

The  liquid  and  solid  excrements  used  as  manure  enabled  this 
surface  of  arable  land  to  produce  as  much  as  the  meadow  land. 

But  notwithstanding  the  amount  of  manure  supplied,  the  field 
was  no  richer  in  the  mineral  f  )od  of  plants  on  the  sixth  year, 
when  it  was  manured  anew,  than  it  was  the  first  year.  In  the 
second  year  after  manuring,  it  contained  less  mineral  food  than 
on  the  first  year ;  and  after  the  fifth  year  it  became  so  much  ex- 
hausted that  it  was  necessary,  in  order  to  obtain  crops  as  rich  as 
the  first  year,  to  give  back  to  the  field  all  the  mineral  constituents 
10  .       .    ,  .     ; 


194  RETROSPECT. 


that  had  been  removed  during  the  five  years'  rotation  ;  this  was 
done,  without  doubt,  by  means  of  the  manure. 

Our  supply  of  manure,  therefore,  effects  only  this  result,  that 
the  soil  of  our  arable  land  is  not  rendered  poorer  than  that  of 
meadow  land  capable  of  yielding  on  the  same  surface  25  cwt.  of 
hay.  From  a  meadow  we  remove  annually,  in  the  hay,  as  great 
an  amount  of  the  constituents  of  the  soil  as  we  do  in  the  crops 
obtained  from  the  arable  land;  and  we  know  that  the  fertility  of 
meadow  land  is  as  dependent  on  the  restoration  of  the  constituents 
of  the  soil,  as  that  of  arable  land  is  upon  the  supply  of  manure. 
Two  meadows  of  equal  surfaces,  but  containing  unequal  quantities 
of  inorganic  food,  are  of  unequal  fertility  under  like  circumstances. 
The  meadow  containing  the  greatest  quantity  of  the  mineral  food 
yields  more  hay,  in  a  certain  number  of  years,  than  the  other 
which  is  poorer  in  mineral  ingredients. 

But  if  we  do  not  restore  to  a  meadow  the  constituents  of  the 
soil  removed  from  it,  its  fertility  decreases. 

The  fertility  of  a  meadow  remains  the  same,  not  only  by  treat- 
ing it  with  solid  or  with  liquid  excrements,  but  it  may  be  retained, 
or  may  be  even  increased  in  fertility  by  the  application  of  mine- 
ral substances  left  behind  after  the  combustion  of  wood  or  of 
other  plants  By  means  of  ashes  we  can  restore  the  impaired 
fertility  of  our  meadow  land.  But  by  the  term  ashes,  we  un- 
derstand the  mineral  food  which  plants  received  from  the  soil. 
When  we  furnish  them  to  our  meadows  we  enable  the  plants 
growing  on  them  to  condense  carbon  and  nitrogen  on  their  surface. 

Now,  does  not  the  action  of  liquid  and  solid  excrements 
depend  on  the  same  cause  ?      For  these  are  but  the  ashes  of 

PLANTS  BURNT  IN  THE  BODIES  OF  MAN  AND  OF  OTHER  ANIMALS. 

Is  fertility  not  quite  independent  of  the  ammonia  conveyed  to 
the  soil  ?  If  we  evaporated  urine,  dried  and  burned  the  solid 
excrements,  and  supplied  to  our  land  the  salts  of  the  urine,  and 
the  ashes  of  the  solid  excrements,  would  not  the  cultivated  plants 
grown  on  it — the  graminese  and  leguminosae — obtain  their  carbon 
and  nitrogen  from  the  same  sources  whence  they  are  obtained  by 
the  gnimincos  and  leguminosae  of  our  meadows  ? 

There  can  scarcely  be  a  doubt  with  regard  to  these  questions, 
when  we  unite  the  information  furnished  by  science  to  that  sup- 
plied by  the  practice  of  agriculture. 


INORGANIC  MANURE.  195 

The  following  rotation  is  adopted  in  Alscce,  as  oeing  the  most 
advantageous ;  it  extends  over  a  period  of  five  years,  during 
which  the  land  is  only  once  manured  : — 

1st  Year.           2d  Year.            3d  Year.            4th  Year.  5th  Year.       6th  Year. 

Manured.  Manured. 

Oats,  or 

Wheat  with  Rye,  or      Potatoes 

Potatoes  or    Wheat          Clover       Fallow  turnips  Barley. 

Beet 

Potash           Silica          Lime       Silica    >  t),  .  Silica  ^ 


Plants.          Plant.         Plant.   Potash  5  P^^^^s      j^^^^    j  Plants, 

Now,  if  we  suppose  that  the  action  of  the  manure  depends 
upon  its  ammonia,  or  amount  of  nitrogen,  then  it  is  obvious  that 
a  progressive  diminution  must  ensue ;  that  the  nitrogen  in  the 
crops  of  the  first  and  second  years  must  amount  to  more  than 
that  contained  in  the  crops  of  the  fourth  and  fifth  years.  But 
this  opinion  is  completely  opposed  to  the  following  proportions,  as 
indicated  by  analysis  : — 

1st  Year.    2d  Year.    3d  Year.    4th  Year.    5tb  Year. 
Nitrogen  in  the  crop  -     -       46  35*4        84*6  560  28-4 

Thus,  in  the  third  and  fourth  years  the  nitrogen  in  the  crops 
amounted  to  much  more  than  the  quantity  contained  in  the  crops 
of  the  first  and  second  years  ;  and  in  the  fifth  year  the  quantity 
was  only  one-fourth  less  than  it  was  in  the  second  year.  Now, 
is  it  possible  or  conceivable  that  the  ammonia  given  in  the  first 
year,  being  a  body  of  great  volatility  and  very  apt  to  evaporate 
along  with  water,  could  be  present  in  greater  quantity  in  the  soil 
during  the  fourth  year  than  it  was  in  the  first  and  second  years  ; 
or  that  it  could  yield  to  the  oats  of  the  fifth  year  the  necessary 
quantity  of  nitrogen  for  their  growth  ? 

But  let  us  admit  that  the  nitrogen  conveyed  to  the  soil  by 
strong  manuring  was  actually  exhausted  in  the  fifth  year  by  the 
different  plants  cultivated  upon  it  ;  and  let  us  then  compare  the 
rotation  employed  in  Alsace,  with  that  adopted  on  one  of  the 
most  fertile  districts  of  the  Rhine.  In  Bingen  there  is  a  nine- 
years'  rotation  followed,  the  plants  suc(jeeding  each  other  in  the 
following  order  : — 


19«  RETROSPECT. 


1st  year.           2d  Year      3d,  4th,  5th,  6th  Years.  7th  Year.        8th  Year.        9th  Year. 

Manured.  Manare<L 

Turnips      Barley  with         Lucern.  Potatoes.       Wheat.         Barley. 

Lucern. 

Six  years  after  manuring,  after  the  supply  of  ammonia  and 
manure  containing  nitrogen,  after  four  succeeding  crops  of  clover, 
and  after  a  crop  of  barley  and  one  of  oats,  the  soil  of  Bingen 
yields  rich  crops  of  potatoes,  wheat,  and  barley,  and  these  suc- 
ceed each  other  at  a  time  when,  according  to  our  assumption,  the 
manured  field  in  Alsace  was  to  be  viewed  as  completely  ex- 
hausted of  its  nitrogen.  Can  it  be  conceived  that  the  ammonia 
of  the  manure  could,  after  the  lapse  of  8 — 9  years,  furnish  the 
nitrogen  to  the  crops  of  wheat  and  barley  ?  But  even  admitting 
this  to  be  the  case,  we  have  then  to  inquire  whence  do  the  corn- 
fields in  Hungary,  in  Sicily,  or  in  the  vicinity  of  Naples,  receive 
their  nitrogen,  for  these  fields  have  never  been  manured  ?  Are 
we  actually  to  believe  that  the  nutrition  of  plants  in  the  fields 
of  moderate  climates  is  subject  to  different  laws  from  those 
governing  the  warmer  and  tropical  regions  ? 

In  Virginia  the  annual  crop  of  nitrogen  in  wheat  amounted  to 
22  lbs.  an  acre,  on  the  smallest  calculation,  or  in  100  years  to 
2200  lbs.  If  we  were  to  suppose  that  this  nitrogen  was  fur- 
nished by  the  field,  each  acre  must  have  contained  it  in  the  form 
of  hundreds  of  thousand  pounds  of  animal  excrements  ! 

The  whole  population  of  Limousin  subsist  upon  milk  and 
sweet  chestnuts,  the  production  of  which,  being  unattended  with 
trouble,  is  ascribed  by  Dupin  as  the  cause  of  their  low  state  of 
intellect.  Without  being  subjected  to  any  system  of  farming, 
this  district  produces  enormous  quantities  of  the  constituents  of 
the  blood,  the  nitrogen  of  which  cannot  have  been  produced  from 
manure. 

For  centuries,  in  Hungary,  wheat  and  tobacco  have  been  cul- 
tivated on  the  same  field,  without  any  supply  of  nitrogen.  Is  it 
possible  that  this  nitrogen  can  have  had  its  origin  in  the  soil  ? 
Our  forests  of  beeches,  chestnuts,  and  oaks,  become  covered  with 
leaves  every  year ;  the  leaves,  sap,  the  acorns,  chestnuts,  cocoa- 
nuts,  the  fruit  of  the  bread-tree,  are  rich  in  nitrogen.  This 
nitrogen  is  not  contained  in  the  soil,  nor  is  it  conveyed  to  the 


EXPERIMENTS  OF  BOUSSINGAULT.  197 

wild  plants  by  the  hand  of  man.  Then  it  is  impossible  to  doubt 
the  source  whence  the  nitrogen  is  obtained.  The  source  of  the 
nitrogen  can  only  be  the  atmosphere.  It  matters  not  in  what 
form  it  is  contained  therein,  or  in  what  form  it  is  taken  from  it  ; 
the  conclusion  is  the  same,  that  tlie  nitrogen  of  wild-growing 
plants  must  be  derived  from  the  atmospliere. 

Are  the  fields  of  Virginia,  the  fields  of  Hungary,  our  own  cul- 
tivated plants,  not  able  to  receive  it  from  the  same  sources  as  the 
wild-growing  vegetation  ?  Is  the  supply  of  nitrogen  in  animal 
excrements  a  matter  of  absolute  indifference  :  or  do  we  obtain 

IN  OUR  FIELDS  A  QUANTITY  OF  THE  CONSTITUENTS  OF  THE  BLOOD, 
ACTUALLY  CORRESPONDING  TO  THE  SUPPLY  OF  AMMONIA  ? 

These  questions  are  completely  solved  by  the  investigations  of 
Boussingault  ;  which  are  so  much  the  more  valuable,  as  they 
were  instituted  with  a  totally  distinct  object  in  view. 

From  the  known  quantity  of  manure  (common  stable  manure) 
which  Boussingault  put  every  five  years  upon  his  field  (amount- 
ing to  four  Hessian  acres),  he  estimated,  by  the  analysis  of  the 
manure,  the  total  quantity  of  nitrogen  furnished  for  the  rotation 
of  five,  years.  For  this  purpose,  the  moist  stable  manure  was 
first  dried  by  exposure  to  the  air  and  to  the  sun,  and  afterwards 
was  further  dried  in  vacuo,  by  exposing  it  to  a  temperature  of 
230^  F. ;  the  manure  thus  treated  was  subjected  to  an  ultimate 
analysis.  The  average  crops  of  the  field,  treated  with  manure, 
were  then  determined  ;  and  the  products,  corn  and  straw,  turnips, 
potatoes,  peas,  clover,  &c.,  were  analysed  for  the  purpose  of 
ascertaining  their  composition  with  reference  io  nitrogen,  carbon, 
hydrogen,  and  ashes.* 

In  this  manner  the  quantities  of  nitrogen  conveyed  to  the  field 
in  the  form  of  manure,  and  reaped  from  it  in  the  crops,  were 
ascertained,  and  could  be  compared  together.  If  the  plants 
depended  for  their  nitrogen  upon  the  manure,  and  did  not  receive 
any  of  that  element  from  the  air  ;  the  nitrogen  of  the  crops  could 

*  The  greatest  number  of  these  analyses — viz.  the  composition  of  pota- 
toes (Boeckmann)  ;  of  beet  and  turnips  (Will)  ;  of  wheat  straw  (Will)  ; 
of  the  carbon  and  nitrogen  of  peas  (Noll  and  Zytowieki)  ;  and  of  their 
carbon  (Playfair),  were  repeated  in  this  laboratory,  and  ascertained  U 
be  perfectly  correct. 


©8  RETROSPECT. 


not  correspond  to  more  than  the  quantity  in  the  manure.  If  the 
crops  contained  more  than  this  quantity,  the  excess  must  have 
been  obtained  from  other  sources,  and  these  could  only  be  in  the 
atmosphere  ;  such  were  the  suppositions  on  which  Boussingault 
proceeded.  According  to  his  estimation,  the  three  rotations* 
yielded  : — 

1st  Rotation.  2d  Rotation.  3d  Rotation.  In  16  years. 
Nitrogen  in  lbs.  -  -  -  501-4  508'4  7072  17170 
in  stable  manure      -     40G-4            406-4            487-6              1300-4 


Excess  of  nitrogen  obtained,  lbs.    95  102  2196  416*6 

In  the  first  and  second  rotation,  the  excess  of  nitrogen  obtained 
was  nearly  equal ;  in  the  third  it  was  twice  as  much. 

Now,  asked  Boussingault — did  each  of  these  plants  possess  the 
power  of  absorbing  and  appropriating  to  their  organism  nitrogen 
from  the  air,  or  was  this  power  confined  only  to  one  of  them  ;  and 
was  the  excess  of  nitrogen  due  to  all  the  various  kinds  of  plants, 
or  was  it  yielded  by  only  one  of  them  ?  A  new  experiment 
seemed  to  him  to  decide  the  question.  Two  successive  crops  of 
corn  were  taken  from  a  fallow-field,  well  manured,  and  the  pro 
duce  amounted  to  : — 

Nitrogen  in  the  crops       -         -         .         ]  74-8  lbs. 
■ the  manure     -        -        -        165-6 

An  excess  of  nitrogen  -         -  9*2  lbs. 

But  this  excess  in  the  crop  is  too  small  not  to  be  liable  to  errors 
in  the  experiment.  Boussingault  concluded  from  it,  that  cereals 
do  not  absorb  nitrogen  from  the  air,  and  that  the  amount  of  nitro- 
gen yielded  in  crops  is  only  equivalent  to  that  contained  in  the 
manures. 

Now,  as  it  had  been  found  that  the  quantity  of  nitrogen  ob- 


Ist  Rotation. 

2d  Rotation. 

3d  Rotation. 

1 

Ye3x 

Potatoes 

Beet 

Potatoes 

2 

" 

Wheat 

Wheat 

Wheat 

3 

(( 

Clover 

Clover 

Clover 

4 

(1 

Wheat             > 
late  Turnips  ) 

Wheat 

1 

Wheat 
late  Turnips 

late  Turni 

ps 

5 

«< 

Oats 

Oats 

Peas 

0 

«( 

Rye 

EXPERIMENTS  OF  BOUSSINGAULT.  199 

tained  in  crops  of  potatoes  and  turnips  scarcely  corresponds  to 
more  than  the  quantity  in  crops  of  wheat,  it  follows  that  they 
could  not  have  tlie  power  to  form  their  azotized  constituents  with- 
out  manure  ;  so  that  nothing  remains,  except  to  ascribe  to  the 
clover  the  excess  of  nitrogen  obtained.  This  explains,  also,  why 
the  excess  is  so  much  greater  in  the  third  rotation  than  in  any  of 
the  preceding  ;  for  it  will  be  remarked,  that  in  the  third  rotation 
a  sixth  crop  was  introduced,  corresponding  to  the  same  family  as 
clover.  If,  therefore,  there  had  been  neither  peas  nor  clover  in 
the  third  rotation,  but,  instead  of  these  plants,  one  of  another 
family,  the  nitrogen  of  the  crop  would  have  amounted  only  to  the 
quantity  supplied  in  the  manure.  Boussingault  concludes  that 
leguminous  plants  alone  possess  the  power  of  appropriating,  as 
food,  nitrogen  from  the  air,  and  that  other  cultivated  plants  do  not 
at  all  possess  this  property.  Hence  the  great  importance  which 
Boussingault  ascribes  to  manures  containing  nitrogen,  for,  ac- 
cording to  his  view,  the  commercial  value  of  a  manure  depends 
on  its  amount  of  nitrogen.  But  all  these  conclusions  are  tho- 
roughly erroneous;  for,  if  they  were  not  so,  it  must  follow  that 
potash,  lime,  and  silica  plants,  unless  they  belonged  to  the  Legu- 
minosse,  would  not  produce  any  nitrogen,  unless  they  were  sup- 
plied with  manure  containing  that  element. 

The  conclusions  of  Boussingault  are  not  only  erroneous  in  their 
applications  to  agriculture,  but  are  incorrect  in  the  methods 
which  he  employs ;  for  the  manure  was  not  given  to  the  fields  in 
the  form  in  which  he  analysed  it. 

Let  us  assume  that  the  manure  which  he  put  upon  his  fields 
possessed  the  same  state  in  which  it  was  analysed  (dried  at 
230^  F.  in  vacuo) ;  then  the  field  would  receive  in  the  sixteen 
years  1300  lbs.  of  nitrogen.  But  the  manure  was  not  put  upon 
the  field  in  an  anhydrous  state,  but,  on  the  contrary,  in  its  natu- 
ral moist  condition,  soaked  with  water  ;  and  we  know  that  all  the 
nitrogen  contained  in  the  manure  in  the  form  of  carbonate  of  am- 
monia is  volatilized  when  it  is  dried  at  a  high  temperature.  The 
nitrogen  of  the  urine  in  the  manure,  which  is  converted  by  putre- 
faction into  carbonate  of  ammonia,  is  not  included  in  the  1300  lbs. 
of  the  above  calculation. 

Human  excrements,  dried  in  the  air  at  ordinary  temperature 


2-jl)  RETROSPECT. 


(poudrette),  lose,  at  230^,  half  of  all  the  nitrogen  contained  in 
them,  in  the  form  of  carbonate  of  ammonia.  Common  stable  ma- 
nure, which  contains  79 — 80  per  cent,  of  water,  must  lose,  when 
heated  to  230°  in  vacuo,  at  least  three  times  as  much  nitrogen 
as  it  retains  ;  that  is,  3-4ths  of  all  the  nitrogen  originally  present 
in  it.  But  if  we  estimate  it  at  haif  of  the  quantity  present  in  the 
dried  excrements,  then  the  field  must  have  received,  in  sixteen 
years,  1950  lbs.  of  nitrogen. 

But  in  sixteen  years,  1517  Ihs.  of  nitrogen  only  were  ob- 
tained, IN  THE  FORM    OF    CORN,  STRAW,  AND    TUBERS  ;    mUch  less, 

therefore,  than  the  quantity  furnisherl  to  the  field.  Hence  his 
erroneous  conclusion,  that  the.  Leguminosas  alone  possess  the 
power  of  condensing  nitrogen  from  the  air ;  and  tliat  it  is  neces- 
sary to  furnish  nitrogen  to  tiio  Grtuulneae,  aixl  to  plants  such  as 
turnips  and  potatoes.  Rut  in  the  same  time,  and  upon  the  same 
surfiice  of  a  good  meadow,  not  receiving  nitrogen,  we  may  obtain 
(on  1  hectare)  2060  lbs.  of  this  element. 

It  is  well  known  that  dried  excrements  form  the  principal  fuel 
in  Egypt,  where  wood  is  scarce.  For  centuries  the  sal  ammo- 
niac used  in  Europe  was  supplied  from  tiie  soot  of  these  excre- 
ments, until  Gravenhorst,  in  the  latter  part  of  last  century, 
discovered  how  to  prepare  it,  and  ijastituted  a  manufactory  at 
Brunswick. 

The  fields  in  the  valley  of  the  Nile  re-ceive  no  manure  of  ani- 
mal origin  except  the  fixed  ingredients  (which  contain  no  nitro- 
gen) of  the  ashes  of  the  burnt  dung;  and  yet  these  fields  have 
been  so  fertile,  for  periods  long  before  our  history  commences, 
that  this  fertility  has  become  a  proverb,  and  is  quite  as  remarkable 
at  the  present  day  as  it  was  in  former  times.  These  fields  be- 
come renovated  by  the  mud  deposited  during  the  inundations  of 
the  Nile  ;  the  mineral  ingredients  of  the  soil  removed  in  the  crops 
are  thus  restored  to  it.  The  mud  of  the  Nile  contains  as  little 
nitrogen  as  the  mud  from  the  Alps,  in  Switzerland,  deposited  on, 
and  fertilizing  our  own  fields  by  the  inundations  of  the  Rhine. 

In  fact,  if  the  mud  of  the  Nile  fertilizes  the  soil,  in  consequence 
of  its  containing  nitrogen,  we  must  suppose  immense  strata  of 
nitrogenized  animal  and  vegetable  matter  to  exist  in  the  mountains 
of  the  interior  of  Africa,  at  heights  above  the  line  of  perpetual 


REVIEW  0[^  PRECEDING  THEORIES.  201 

congelation,  where,  owing  to  the  absence  of  all  vegetation,  no  ani. 
mal,  not  even  a  bird,  can  now  find  nourishment. 

Cheese  must  be  formed  from  the  plants  upon  which  cows  feed. 
The  meadows  of  Holland  must,  of  course,  obtain  their  nitrogen 
from  the  air.  The  milch  cows  in  Holland  remain  on  the  fields 
both  day  and  night ;  all  the  salts  contained  in  their  fodder 
must  remain  upon  the  fields  in  the  form  of  urine  and  of  solid 
excrements,  a  small  quantity  proportionately  being  removed  in 
the  cheese. 

The  condition  of  fertility  of  these  meadows  can  change  as  little 
as  that  of  our  fields,  which,  although  not  grazed  upon,  receive,  in 
the  form  of  manure,  the  greatest  part  of  the  ingredients  removed 
from  them. 

In  the  cheese  districts  of  Holland,  these  ingredients  remain  on 
the  meadows  ;  while  in  our  system  of  farming,  they  are  collected 
at  home,  and  carried,  from  time  to  time,  to  our  fields.  The  ni- 
trogen of  the  urine,  and  that  of  the  solid  excrements  of  the  cow, 
are  obtained  in  Holland  from  the  air ;  and  from  the  same  source 
must  be  obtained  the  quantity  of  that  element  contained  in  all 
the  kinds  of  cheese  prepared  in  Holland,  Switzerland,  and  other 
countries. 

The  meadows  in  Holland,  for  centuries,  have  produced  millions 
of  cvvts.  of  cheese  :  there  are  annually  exported  from  this  country 
thousands  of  cwts.  of  this  substance ;  and  yet  this  exportation 
does  not  in  any  way  diminish  the  productiveness  of  their  meadows, 
although  they  have  never  received  from  the  hand  of  man  more 
nitrogen  than  they  originally  contained. 

Hence  it  is  quite  certain,  that  in  our  fields,  the  amount  of  nitro- 
gen in  the  crops  is  not  at  all  in  proportion  to  the  quantity  supplied 
in  the  manure,  and  that  the  soil  cannot  be  exhausted  by  the  ex- 
portation of  products  containing  nitrogen  (unless  these  products 
contain  at  the  same  time  a  large  amount  of  mineral  ingredients), 
because  the  nitrogen  of  vegetation  is  furnished  by  the  atmosphere, 
and  not  by  the  soil.  Hence  also  we  cannot  augment  the  fertility 
of  our  fields,  or  their  powers  of  production,  by  supplying  them 
with  manures  rich  in  nitrogen,  or  with  ammoniacal  salts  alone, 
The  crops  on  a  field  diminish  or  increase  in  exact  proportion  t<>' 
10*  .  -    "   ^ 


•  202  REVIEW  OF  PRECEDING  THEORIES. 

the  diminution  or  increase  of  the  mineral  substances  conveyed  to 
it  in  manure. 

The  formation  of  the  constituents  of  the  blood,  and  of  the  vege- 
table substances  containing  nitrogen  existing  in  cultivated  plants, 
depends  upon  the  presence  of  certain  substances  contained  in  the 
soil.  When  these  ingredients  are  absent,  nitrogen  will  not  be 
assimilated,  however  abundantly  it  may  be  supplied.  The  am- 
monia of  animal  excrements  exerts  a  favorable  influence  only 
because  it  is  accompanied  by  other  substances  necessary  for  its 
conversion  into  the  constituents  of  blood.  When  these  conditions 
are  furnished  with  ammonia,  the  latter  becomes  assimilated.  But 
when  the  ammonia  is  absent  from  the  manure,  the  plants  extract 
their  nitrogen  from  the  ammonia  of  the  air ;  to  which  it  is  again 
restored  by  the  decay  and  putrefaction  of  dead  animal  and  vege- 
table remains. 

Ammonia  accelerates  and  favors  the  growth  of  plants  on  all 
kinds  of  soil,  in  which  exist  the  conditions  for  its  assimilation  ; 
but  it  is  quite  without  action  upon  the  production  of  the  consti- 
tuents of  the  blood,  when  these  conditions  do  not  exist. 

It  is  possible  to  conceive  that  asparagin  (the  active  ingredient 
of  asparagus)  and  the  ingredients  so  rich  in  nitrogen  and  sulphur, 
oC  mustard  and  of  all  Cruciferse,  could  be  generated  without  the 
co-operation  of  the  ingredientsof  the  soil.  But  if  it  were  possible 
to  form  the  organic  constituents  of  blood  existing  in  plants,  with- 
out the  aid  of  the  inorganic  ingredients  of  the  blood,  such  as 
potash,  soda,  phosphates  of  soda  and  of  lime,  they  would  be  of 
very  little  use  to  animals,  and  could  not  fulfil  the  purposes  for 
which  they  were  destined  by  the  wisdom  of  the  Creator.  Blood, 
milk,  and  muscular  fibre  cannot  be  formed  without  the  aid  of 
alkalies  and  of  phosphates  ;  and  bones  cannot  be  produced  without 
phosphate  of  lime. 

In  urine,  and  in  the  solid  excrements  of  animals,  and  in  guano, 
we  furnish  ammonia,  and  therefore,  nitrogen,  in  our  plants. 
This  nitrogen  is  accompanied  by  the  mineral  food  of  plants,  and 
actually  in  the  same  proportion  as  both  exist  in  the  plants  which 
served  the  animals  for  food  ;  or,  what  is  the  same  thing,  in  the 
same  proportion  in  which  both  are  capable  of  being  applied  for  a 
new  generation  of  plants. 


REVIEW  OF  PRECEDING  THEORIES.  30a 

The  action  of  an  artificial  supply  of  ammonia  as  a  source  of 
nitrogen,  is  limited,  like  that  of  humus  as  a  source  of  carbonic 
acid,  to  a  gain  in  point  of  time  ;  in  other  words  to  the  ac- 
celeration of  the  development,  in  a  given  time,  of  our  cultivated 
plants. 

By  means  of  ammonia,  in  the  form  of  animal  excrements,  we 
increase  the  quantity  of  the  constituents  of  blood  in  our  cultivat- 
ed plants — an  action  which  the  carbonate  or  sulphate  of  ammonia 
alone  never  exerts. 

In  order  to  obviate  any  misunderstanding,  we  must  again  draw 
attention  to  the  fact  that  this  explanation  is  not  in  any  way  con- 
tradicted by  the  effects  produced  on  the  application  of  artificial 
ammonia,  or  of  its  salts.  Ammonia  is,  and  will  continue  to  be 
the  source  of  all  the  nitrogen  of  plants  :  its  supply  is  never  in- 
jurious ;  on  the  contrary,  it  is  always  useful,  and,  for  certain 
purposes,  indispensable.  But,  at  the  same  time,  it  is  of  great 
importance  for  agriculture,  to  know  with  certainty  that  the  sup- 
ply of  ammonia  is  unnecessary  for  most  of  our  cultivated  plants, 
and  that  it  may  be  even  superfluous,  if  only  the  soil  contain  a 
sufficient  supply  of  the  mineral  food  of  plants,  when  the  ammonia 
required  for  their  development  will  be  furnished  by  the  atmo- 
sphere. It  is  also  of  importance  to  know,  that  the  rule  usually 
adopted  in  France  and  in  Germany  of  estimating  the  value 
of  a  manure  according  to  the  amount  of  its  nitrogen,  is  quite 
fallacious,  and  that  its  value  does  not  stand  in  proportion  to  its 
nitrogen. 

By  an  exact  estimation  of  jhe  quantity  of  ashes  in  cultivated 
plants,  growing  on  various  kmds  of  soils,  and  by  their  analysis, 
we  will  learn  those  constituents  of  the  plants  which  are  variable, 
and  those  which  remain  constant.*     Thus  also  we  will  attain  a 

*  The  following  analyses  of  ashes  may  be  added  to  those  formerly  given : 


Ashes  of  Clover 

Ashes  of 

(TrifoUum  pratense). 

Sainfoin. 

Silica  - 

-     5 -438 

2-79 

Sulphate  of  potash 

-     3080 

3-87 

Chloride  of  sodium 

-     1-670 

2-37 

Carbonate  of  potash 

-  12-728 

9  93 

Carbonate  of  soda 

-  13-528 

1716 

Carbonate  of  lime 

-  dS-91d 

3255 

204  REVIEW  OF^  PRECEDING  THEORIES. 

knowledge  of  the  quantities  of  all  the  constituents  removed  from 
the  soil  by  different  crops. 

The  farmer  will  thus  be  enabled,  like  a  systematic  manufac- 
turer, to  have  a  book  attached  to  each  field,  in  which  he  will 
note  the  amount  of  the  various  ingredients  removed  from  the  land 
in  the  form  of  crops,  and  therefore  how  much  he  must  restore  to 
bring  it  to  its  original  state  of  fertility.  He  will  also  be  able  to 
express  in  pounds  weight,  how  much  of  one  or  of  another  ingre- 
dient of  soils  he  must  add  to  his  own  land,  in  order  to  increase  its 
fertility  for  certain  kinds  of  plants. 

These  investigations  are  a  necessity  of  the  times  in  which  we 
live  ;  but  in  a  few  years,  by  the  united  diligence  of  chemists  of 
all  countries,  we  may  expect  to  see  the  realization  of  these  views  ; 
and  by  the  aid  of  intelligent  farmers,  we  may  confidently  expect 
to  see  established,  on  an  immovable  foundation,  a  rational  system 
of  farming  for  all  countries  and  for  all  soils. 


Ashes  of  Clover 

Vshes  of 

( Trifolium  pratcnse.) 

Sainfoin. 

Magnesia      -         -         - 

-     4-160 

911 

Phosphate  of  iron 

-     1-240 

0-64 

Phosphate  of  lime 

-  : 1-970 

15-37 

Phosphate  of  magnesia 

-     G-790 

3-9S 

Carbonaceous  matter    - 

-     0-160 

0-36 

98-980  98*13 


SGORCES  OF  AMMONIA.  20S 


SUPPLEMENTARY  CHAPTERS. 

I. — The  Sources  of  Ammonia. 

When  animals  appeared  on  the  surface  of  the  earth,  it  cannot  be 
doubted  that  means  must  have  been  provided  for  their  sustenance 
and  increase,  or  in  other  words,  that  plants  must  have  existed  to 
furnish  them  with  food.  But  it  is  quite  as  obvious  that,  at  the 
period  of  the  formation  of  the  vegetable  world  itself,  the  condi- 
tions must  have  existed  in  the  soil  and  in  the  atmosphere,  neces- 
sary for  the  exercise  of  vegetable  life.  With  the  same  certainty 
with  which  we  presuppose  the  existence  of  a  compound  of  carbon 
to  furnish  that  element  to  vegetation,  we  must  also  assume  the 
contemporaneous  presence  of  a  compound  of  nitrogen,  such  as  at 
the  present  day  yields  that  element  to  plants. 

If  we  disregard  the  fundamental  principle  on  which  all 
inquiries  into  nature  ought  to  proceed,  then  we  may  assume, 
a  priori,  according  to  our  will  and  pleasure,  that  other  compounds 
of  carbon,  differing  from  carbonic  acid,  formerly  took  part  in  the 
vital  processes  of  plants  ;  but  if  we  still  retain  the  foundation  of 
all  scientific  inquiry,  namely,  induction  from  facts,  then  we  can- 
not admit  the  existence  of  these  hypothetical  compounds  of  car- 
bon, either  because  they  are  totally  unknown  to  us,  or  that  their 
existence  is  doubtful. 

The  same  reasoning  must  be  adopted  in  the  case  of  nitrogen. 
Science  is  at  present  ignorant  of  any  compound  of  nitrogen  be- 
sides ammonia,  capable  of  yielding  nitrogen  to  wild  plants  on  all 
parts  of  the  earth's  surface.  No  other  such  compound  of  nitrogen 
has  been  indicated,  or  even  hypothetically  supposed  to  exist,  and 
designated  by  a  name,  in  the  case  of  cultivated  plants ;  and  there- 
fore, until  a  second  source  of  nitrogen  is  discovered,  we  must,  ill: 
scsience^-yiow.  ammonia  a&  tlie  on?v-, sou  roe.-  .     ...    '     .,   r 


906  SOURCES  OF  AMMONIA. 


Now,  it  may  be  asked,  Is  there  no  means  of  increasing  the 
amount  of  ammonia  which  exists  in  the  atmosphere,  as  well  as 
in  the  form  of  plants  and  animals,  and  which  we  shall  assume  to 
be  a  limited  quantity  ?  This  question  may  be  repeated  in  another 
form,  viz.  Whether  there  exist  undoubted  facts  for  the  opinion 
that  the  nitrogen  of  the  air  possesses,  under  any  condition,  the 
power  of  assuming  the  form  of  ammonia,  or  of  any  other  com- 
pound of  nitrogen  ?  Besides  nitric  acid  and  ammonia,  we  do 
not  know  any  other  compounds  of  nitrogen,  except  those  exist- 
ing in  plants  and  animals,  or  which  may  be  prepared  from  them. 
With  the  exception  of  these  compounds,  nitrogen  exists  only  in 
the  form  of  a  gas,  which  has  been  recognised  as  one  of  the  prin- 
cipal constituents  of  air. 

An  ignorance  of  the  proper  sources  whence  vegetation  receiv- 
ed its  nitrogen,  led  philosophers  long  since  to  the  opinion,  that 
plants  must  possess  the  power,  in  some  way  or  another,  of  appro- 
priating the  nitrogen  of  the  air  in  their  vital  processes.  In  fact, 
until  it  was  known  that  ammonia  formed  a  constituent  of  the  air, 
there  was  scarcely  any  reason  to  doubt  this  power  of  plants ;  for 
how  otherwise  were  wild  plants  to  obtain  the  nitrogen  of  their 
azotized  constituents  ? 

But  ammonia  was  known  and  considered  only  as  a  product  of 
the  destruction  and  decomposition  of  the  organism.  The  pro- 
duction and  formation  of  ammonia  presupposed  the  existence  of 
plants  or  animals.  Hence  there  have  arisen  two  views  respect- 
ing the  origin  of  ammonia,  the  correctness  of  which  we  have  as 
little  means  of  establishing  by  decisive  evidence,  as  we  have  of 
answering  the  questions — Whether  the  hen  existed  before  the 
egg,  or  the  egg  before  the  hen  ;  or  whether  water  was  first  creat- 
ed as  water,  or  as  hydro jjen  and  oxygen  ?  We  have  sufficient 
reason  to  believe  that  the  vegetable  preceded  the  animal  kingdom  ; 
and  we  assume,  that  before  plants  were  formed,  the  conditions 
essential  for  their  life  and  increase  must  have  existed  ;  and  that 
then,  as  well  as  now,  ammonia  must  have  been  a  constituent  of 
the  air ;  and  that  the  destruction  of  plants  did  not  precede  the 
formation  of  ammonia.  Now,  it  is  obvious  that  if  the  same 
causes  now  continue  in  action,  as  those  which  effected  the  forma- 
ts of  ammonia  at  the  commencement  of  vegetation,— if  their 


FORMATION  OF  MATTER.  207 


action  resulted  in  the  conversion  of  the  gaseous  nitrogen  into 
ammonia, — then,  at  the  present  day,  during  every  moment,  am- 
monia must  be  forming,  and  the  amount  of  that  previously  exist- 
ing will  be  increased.  It  is  natural  to  the  mind  of  man  to 
ende-avor  to  solve  questions  of  this  kind,  however  small  may  be 
the  expectation  of  success.  It  is  known  that  the  crust  of  the 
earth  consists  of  compounds  of  oxygen  with  metals  or  with  other 
radicals  ;  and  the  view  appears  quite  admissible,  that  silica  has 
been  formed  from  silicon  and  oxygen  ;  peroxide  of  iron  from 
iron  and  oxygen  ;  and,  to  follow  up  the  idea,  magnesia  and  potash 
have  been  produced  from  oxygen,  magnesium,  and  potassium. 
And  yet  it  is  utterly  impossible  to  assign  a  cause  which  prevent- 
ed the  union  of  the  oxygen  with  potassium  or  magnesium  before 
the  time  that  this  combination  actually  took  place.  Was  there, 
it  may  be  asked,  a  time  when  the  individual  elements  floated  to- 
gether in  Ghaos,  without  possessing  any  kind  of  affinity  ?  In 
what  condition  then  was  the  chlorine  of  common  salt  or  the  carbon 
of  carbonic  acid  ?  It  is  obvious  that  no  answers  can  be  given  to 
questions  respecting  the  origin  of  matteri  If,  then,  we  are  una- 
ble to  afford  any  more  satisfactory  explanation  of  the  origin  of 
ammonia,  than  we  are  able  to  do  of  the  other  compounds  occur- 
ring upon  the  earth,  we  must  rest  satisfied  that  these  questions 
will  either  never  be  solved,  or  that  they  will  not  be  so  until  a 
future  period. 

The  ferruginous  earths  in  the  primitive  rocks  of  South  Ame- 
rica (Boussingault),  and  of  Sweden  (Berzelius), — in  fact  all 
ferruginous  earths  hitherto  examined, — yield,  on  being  heated, 
a  certain  amount  of  water  containing  appreciable  quantities  of 
ammonia.  Whence  has  this  ammonia  had  its  origin  ?  Accord- 
ing to  the  logic  of  Aristotle,  the  occurrence  of  ammonia  in  the 
ferruginous  earths  was  susceptible  of  a  satisfactory  explanation. 

We  may  assume  that  water  is  the  only  original  compound  of 
hydrogen  occurring  in  nature  ;  other  bodies  containing  that  ele- 
ment are  products  of  the  decomposition  of  water,  from  which 
they  have  procured  this  hydrogen. 

Ammonia  has  been  formed  like  other  compounds  of  hydrogen ; 
the  ferruginous  eaith  was  formerly  iron,  which  we  may  suppose 
to  have  becdme  oxidized  at  the  expense  of  wator,  in  which  cas© 


908  SOURCES  OF  AMMONIA. 

peroxide  of  iron  would  be  formed,  and  hydrogen  become  liberat- 
ed. Now,  if  we  assume  that  hydrogen,  at  the  moment  of  its 
liberation,  is  able  to  unite  with  nitrogen  gas  in  contact  with  it, 
and  dissolved  in  water,  then  ammonia  would  be  produced,  and 
would  remain  in  union  with  the  peroxide  of  iron.  It  is  certain 
that  this  explanation  of  the  origin  of  ammonia  in  peroxide  of 
iron  would  be  perfectly  satisfactory,  if  it  were  ascertained 
with  some  degree  of  probability  that  peroxide  of  iron  has 
had  its  origin  by  oxidation  at  the  expense  of  water,  and  that 
the  nitrogen  of  air  is  capable  of  uniting  with  hydrogen  at 
the  instant  of  its  liberation.  On  this  view  we  might  suppose, 
that  although  there  was  a  limit  to  the  formation  of  ammonia, 
under  former  conditions,  when  ferruginous  earth  was  produced, 
that  by  the  simultaneous  occurrence  of  the  same  or  of  analogous 
conditions  at  the  present  day,  ammonia  might  still  be  produced. 

But  the  decomposition  of  water,  by  means  of  iron,  is  effected 
under  such  circumstances  as  appear  to  exclude  the  simultaneous 
production  of  ammonia. 

Iron  does  not  decompose  water  at  the  ordinary  temperatures, 
and  at  higher  temperatures — at  the  boiling  point  of  water,  for 
example — nitrogen  does  not  remain  any  longer  in  solution.  When 
a  stream  of  nitrogen  is  made  to  pass  along  with  water  over  iron 
filings  heated  to  redness,  the  nitrogen  is  again  obtained  unaltered 
although  it  be  mixed  with  hydrogen.  It  is  easily  explained  why  am- 
monia cannot  be  formed  in  this  case,  for  ammoniacal  gas  in  contact 
with  iron  at  high  temperatures,  is  decomposed  into  its  constituents. 

When  finely  divided  hydrate  of  peroxide  of  iron  is  placed  in 
contact  with  metallic  iron,  a  decomposition  of  water  takes  place 
at  a  slightly  elevated  temperature,  and  hydrogen  gas  is  evolved, 
while  magnetic  oxide  of  iron  is  produced.  As  hydrated  peroxide 
of  iron  acts  as  an  acid  in  this  case,  we  should  here,  as  indeed 
universally,  when  metals  are  dissolved  in  acids  with  the  evolution 
of  hydrogen,  obtain  in  the  solution  a  salt  of  ammonia,  if  ammonia 
had  been  formed. 

But  hitherto  the  presence  of  ammonia  under  the  circumstances 
has  not  been  detected  ;  and  it  has  further  been  shown  satisfactorily, 
that  when  water  holding  air  in  solution  is  decomposed  by  a  stream 
of  electricity,  the  hydrogen  evolved  is  accompanied  by  a  certain 


RELATION  OF  NITROGEN  TO  HYDROGEN.  2«i 

quantity  of  nitrogen  gas,  which  could  not  be  the  case  if  nascent 
hydrogen  were  able  to  form  ammonia. 

It  has  been  considered  as  a  certain  proof  of  the  formation  of 
ammonia  from  the  nitrogen  of  the  air,  that  peroxide  of  iron, 
formed  by  the  rusting  of  iron  in  the  air,  contains  a  certain  quan- 
tity of  ammonia ;  but  air  itself  contains  ammonia,  which  pos- 
sesses a  considerable  affinity  for  peroxide  of  iron.  Marshall 
Hall  has  shown  the  inaccuracy  of  the  view  that  water  is  decom- 
posed in  this  case  ;  and  further  experiments,  instituted  in  this 
laboratory  for  the  especial  purposeof  deciding  this  question,  have 
shown,  that  when  air  is  freed  from  its  ammonia,  by  being  con- 
ducted through  concentrated  sulphuric  acid,  before  being  brought 
in  contact  with  the  rusting  iron,  the  oxide  then  formed  does  not 
contain  a  trace  of  ammonia. 

Braconnot*  has  shown  that  most  basalts,  trap,  granite  from 
Rochepon,  and  from  Bresse  ;  syenite,  amphibolite,  wakit  (a  lava)  ; 
basalt,  from  Baden ;  quartz,  from  Gerordines ;  pegmatite,  and 
many  other  minerals,  yield,  by  dry  distillation,  water  containing 
a  sensible  quantity  of  ammonia. 

These  facts  cannot  be  explained  by  the  interpretation  above 
given  to  the  occurrence  of  ammonia  in  ferruginous  earth,  namely, 
the  oxidation  of  iron  at  the  expense  of  water ;  but  there  cannot 
be  any  doubt  that  the  ammonia  has  had  a  similar  origin  in  all 
these  cases,  although  that  origin  cannot  be  ascribed  to  an  oxida- 
tion of  iron. 

The  question — whether  the  nitrogen  of  the  air  possesses  the 
power  of  uniting  with  hydrogen  at  the  moment  of  its  liberation 
from  water  ?  has  been  lately  made  the  subject  of  exact  experi- 
ments, although  with  very  different  objects  in  view.  Will  and 
Varrentrapp  applied  to  the  quantitative  estimation  of  nitrogen  in 
organic  bodies  the  known  fact,  that  the  nitrogen  of  bodies  con- 
taining that  element  is  evolved  in  the  form  of  ammonia,  when 
they  are  heated  to  redness,  mixed  with  potash.  By  combining 
the  ammonia  with  an  acid,  and  converting  it  into  the  salt  termed 
chloride  of  platinum  and  ammonia,  the  ammonia  generated  may 
be  weighed  with  ease,  and  the  quantity  of  nitrogen  may 
be  calculated  from  the  known  composition  of  this  salt.  A  groat 
*  Annales  de  Chimie  et  de  Physique,  tome  Ixvii.,  p.  104,  k,c. 


^^0  SOURCES  OF  AMMONIA. 

number  of  analyses  of  compounds,  in  which  the  quantity  of  ni- 
trogen was  known,  showed  that  this  mode  of  procedure  answered 
completely  the  object  in  view  ;  until  certain  experiments  by 
Reiset  were  published,  in  which  he  obtained  ammonia  by  this 
process  from  substances  such  as  sugar,  &;c.,  which  were  quite 
destitute  of  nitrogen.  Reiset,  therefore,  assumed  that  the  nitro- 
gen of  air  contained  in  the  pores  of  the  mixture  was  the  cause  of 
the  formation  of  ammonia,  and  that,  unless  this  air  were  excluded, 
the  method  of  analysis  was  incorrect  and  objectionable. 

New  experiments,  repeated  with  the  utmost  care  by  Will,  have 
shown  that  in  circumstances  similar  to  those  formerly  observed 
by  Faraday,  ammonia  is  actually  obtained  from  matters  destitute 
of  nitrogen,  when  they  are  heated  to  redness  with  potash  ;  but 
that,  by  excluding  ammonia  itself,  nitrogen  cannot  be  made  ,to 
unite  with  hydrogen  in  a  nascent  state,  and  that  ammonia  can- 
not be  produced  from  these  elements. 

The  admirable  experiments  of  Faraday  (Quarterly  Journal  of 
Science,  xix.,  p.  16)  prove  that,  in  all  the  cases  in  which  ammonia 
was  obtained  by  heating  to  redness  a  substance  destitute  of  nitro- 
gen with  hydrate  of  potash,  the  ammonia  existed  ready  formed 
in  the  substance,  or  in  the  hydrate  of  potash.  There  are  no  ob- 
servations more  convincing  of  the  extraordinary  diffusion  of  am- 
monia, which  exists  in  all  places  where  atmospheric  air  is  to  be 
found.  That  the  reader  may  judge  properly  of  Faraday's  experi- 
ments, I  consider  it  important  to  describe  them  here  in  detail. 

After  Faraday  had  observed  that  woody  fibre,  linen,  oxalate  of 
potash,  and  a  number  of  other  substances  free  from  nitrogen, 
evolved  ammonia  on  being  heated  with  soda,  potash,  hydrate  of 
lime,  &c.,  he  endeavored  to  ascertain  the  conditions  under  which 
the  formation  of  ammonia  ensued  ;  and  in  the  first  place,  he  ex- 
amined the  alkalies.  Hydrate  of  potash,  whether  made  from 
potashes,  cream  of  tartar,  or  potassium,  behaved  exactly  in  the 
same  manner.  The  organic  substances,  when  heated  alone,  had 
no  reaction  on  turmeric  ;  but  when  heated  with  the  alkalies,  a 
disengagement  of  ammonia  ensued. 

It  was  then  to  be  supposed  that  the  nitrogen  of  the  air  sur- 
rounding the  substances  might  take  a  part  in  the  formation  of 
ammonia :  but  this  was  very  improbable :   for  it  is  known  that 


FARVDAY'S  EXPERIMENTS.  Htl 

the  air  contains  oxygen,  whicii  was  never  observed  to  unite  with 
the  liberated  hydrogen  undor  the  same  circumstances,  although 
its  affinity  for  that  element  is  infinitely  greater  than  for  nitrogen. 

According  to  this  supposition,  the  nitrogen  of  the  air  must 
have  formed  ammonia  by  uniting  with  the  hydrogen  of  the 
decomposed  water,  although  at  tiie  same  time  there  was  present 
oxygen,  for  which  hydrogen  has  a  much  greater  affinity. 

The  experiments  were  repeated  in  an  atmosphere  of  pure  hy- 
drogen, prepared  from  water  which  was  previously  freed  from 
all  air  by  long-continued  boiling.  But  in  this  case  also,  where 
all  nitrogen  was  excluded,  the  presence  of  ammonia  was  observed. 
Hence,  Faraday  concluded  that  there  must  be  an  unknown 
cause  of  the  formation  of  ammonia. 

Now,  when  it  is  known  that  ammonia  is  a  constituent  of  the 
air ;  that  it  is  present  wherever  the  air  is  found  ;  that  it  is  itself 
a  coercible  gas,  which  is  condensed  on  the  surface  of  solid  bodies 
in  much  larger  proportion  than  air;  and  further,  when  it  is 
known  that  it  exists  in  distilled  water,  these,  and  other  still  more 
incomprehensible  experiments  of  Faraday,  are  explained  in  a  very 
simple  manner. 

Fine  and  bright  iron  wire,  introduced  into  fused  potash,  causes 
the  evolution  of  ammonia,  which  soon  ceases ;  but  a  new  evolu- 
tion takes  place  when  a  second  portion  of  polished  iron-wire  is 
introduced  (Faraday). 

Zinc  introduced  into  potash  in  a  state  of  fusion,  occasions  an 
immediate  evolution  of  ammonia  and  hydrogen  gas  ;  but  althougii 
the  conditions  for  the  possible  formation  of  ammonia  continue 
(zinc,  air,  and  nascent  hydrogen),  the  quantity  of  ammonia  gene- 
rated does  not  increase  ;  but,  by  the  addition  of  fresh  zinc,  or 
of  hydrate  of  potash,  a  new  quantity  of  ammonia  may  be 
detected. 

Some  potash  and  zinc  were  heated  together  ;  a  part  of  the  mix- 
ture was  then  placed  in  a  flask,  which  was  immediately  closed, 
while  another  part  was  dissolved  in  water,  the  clear  solution  dried, 
and  laid  aside  for  24  hours.  After  this  time  had  elapsed,  the 
first  portion  j:ave  scarcely  perceptible  t;  aces  of  ammonia.  The 
Other  gave  very  appreciable  indications  of  its  presence,  apparently 


213  SOURCES  OF  AMMONIA. 


OS  if  the  substances  which  were  the  source  of  ammonia  were 
derived  from  the  air,  during  the  operation  (Faraday). 

White  clay  from  Cornwall,  after  being  heated  to  redness  and 
exposed  for  a  week  to  the  air,  yielded  ammonia  abundantly,  when 
heated  in  a  tube.  But  when  the  clay  was  preserved  in  a  good 
stoppered  bottle,  after  being  heated  to  redness,  this  effect  was  not 
produced. 

Tlie  observations  which  proved  most  undoubtedly  that  in  all 
these  cases  the  ammonia  was  obtained  from  the  air  and  condensed 
on  the  surface  of  these  materials,  are  the  following  (Faraday)  : — 

Sea-sand  was  heated  to  redness  in  a  crucible,  and  allowed  to 
cool  on  a  plate  of  copper ;  12  grains  of  the  sand  were  then 
placed  in  a  clean  glass  tube  ;  and  an  equal  quantity,  shaken  upon 
the  hand,  was  allowed  to  remain  there  for  a  i^ew  moments,  being 
stirred  about  with  the  fingers,  after  which  it  was  introduced  into 
a  second  tube  by  means  of  platinum  foil,  taking  care  that  the 
grains  of  sand  were  not  brought  in  contact  with  any  othijr  animal 
substance  (Faraday). 

When  the  first  tube  was  heated,  it  gave  no  sign  of  ammonia 
to  turmeric  paper  ;  but  the  second  tube  did  so  in  very  appreciable 
quantity.  For  the  sake  of  precaution  the  tubes  used  in  these 
experiments  were  not  cleansed  by  tow  or  cloth,  but  unused  tubes 
were  taken,  and  before  being  employed  they  were  heated  to 
redness  in  a  stream  of  air  (Faraday). 

Some  asbestos  heated  to  redness,  and  introduced  into  a  tube 
with  metallic  tongs,  gave,  when  heated,  no  indication  of  ammonia  ; 
while,  on  the  contrary,  another  portion,  which  had  been  simply 
pressed  with  the  finger,  yielded  immediate  indications  of  am- 
monia when  heated  in  a  tu[>e  (Faraday). 

Now  it  is  known  that  ammonia  evaporates  by  the  skin,  that 
sweat  contains  salts  of  ammcnia  ;  and  nothing  can  be  more  certain 
than  that,  in  the  experiments  last  described,  and  also  in  those  of 
the  burnt  sand  exposed  to  air,  ammonia  must  have  condensed  on 
the  surface  of  the  sand  or  of  the  asbestos. 

These  experiments  explain  in  a  natural  manner  the  existence 
of  ammonia  in  earth  from  which  plants  and  animals  are  entirely 
absent,  and  also  of  the  formation  of  nitre  in  mixtures  of  earth* 
containing  vegetable  matter. 


FARADAY'S  EXPERIMENTS.  '«« 

All  observations  in  our  times  lead  to  the  conclusion  that  the 
nitrogen  of  the  air  does  not  possess  the  property  of  being  con- 
verted into  ammonia ;  and,  whatever  reasons  there  may  exist  for 
the  probability  of  this  conversion,  we  are  by  no  means  entitled 
to  elevate  to  the  rank  of  a  principle  the  mere  opinion  that  a  part 
of  the  nitrogen  of  plants  arises  from  this  source,  as  it  is  an  hy- 
pothesis standing  in  complete  contradiction  to  all  the  knowledge 
which  we  have  yet  attained. 

All  experiments  which  appear  to  piove  that  the  nitrogen  of  the 
air  becomes  fixed  in  the  organism  of  certain  plants, — that  peas 
and  beans,  for  example,  vegetating  in  a  soil  perfectly  destitute  of 
animal  matters,  must  possess  the  power  of  appropriating  the  ni- 
trogen of  the  atmosphere, — cannot  now  have  the  smallest  value, 
when  it  is  known  that  the  air  contains  ammonia  as  a  constant 
ingredient.  It  must  be  recollected  that  these  experiments  were 
instituted  in  districts  in  which  the  atmosphere  is  much  richer  in 
ammonia  than  in  the  free  fields,  and  that  the  distilled  water,  with 
which  the  plants  were  treated,  was  obtained  from  spring-water, 
and  contained  a  much  larger  quantity  of  carbonate  of  ammonia 
than  rain-water.  Hence,  there  is  no  reason  to  ascribe  the  in 
crease  of  nitrogen  in  the  seeds,  leaves,  and  stems,  to  a  source 
which  was  only  imagined  to  exist,  because  the  quantity  of  am- 
monia in  the  water  and  air  was  not  considered,  and  the  founda* 
tion,  therefore,  of  the  true  explanation  was  altogether  wanting. 

Chemical  experiments  have  shown  that  ammonia  is  not  only  the 
product  of  the  decay  and  putrefaction  of  animal  bodies,  but  thai 
it  is  also  capable  of  being  generated  in  many  chemical  processes, 
when  nitrogen,  at  the  moment  of  its  liberation  from  compounds 
containing  it,  is  offered  to  hydrogen ;  in  such  a  case,  they  unite 
together  and  form  ammonia. 

Compound  gases  containing  nitrogen  as  a  constituent  (cyanogen, 
nitric  oxides,  nitrous  oxides),  are  converted  into  ammonia  when 
they  are  mixed  and  conducted  ever  spongy  platinum  heated  to 
redness  (Kuhlmann),  or  over  peroxide  of  iron  (Reiset). 

When  steam  is  conducted  over  red-hot  wood  charcoal  contain- 
ing nitrogen,  there  is  obtained,  among  other  products,  hydrocyanic 
•acid,  which  is  converted  into  ammonia  and  formic  acid  when 
treated  with  alkalies. 


914  IS  NITRIC  ACID  FOOD  FOR  PLANTS  ? 

The  nitrogen  of  nitric  acid,  when  placed  in  contact  with  hydro- 
gen at  the  moment  of  its  liberation,  as  in  the  solution  of  tin,  or  by 
fusing  nitrates  with  potash  and  organic  substances,  is  converted 
into  the  compound  of  hydrogen.  In  all  cases  in  which  we  expose 
to  a  high  temperature  a  body  containing  nitrogen  and  caustic 
potash,  its  nitrogen  assumes  the  form  of  ammonia. 

The  nitrogen  of  an  organic  body,  of  vegetable  or  animal  mat- 
ter, or  of  the  charcoal  produced  from  them,  arises  from  the  am- 
monia which  the  plant  contained  and  abstracted  from  the  atmo- 
sphere  :  it  enters,  in  the  processes  of  decomposition  alluded  to,  into 
its  original  form,  and  assumes  the  condition  of  ammonia. 

But  these  instances  cannot  be  cited  as  proper  examples  of  the 
formation  of  ammonia,  nor  can  they  be  considered  with  reference 
to  the  question  which  we  have  now  been  discussing. 


IS  NITRIC  ACID  FOOD  FOR  PLANTS? 

Before  we  can  examine  the  opinion  whether  nitric  acid  be  a 
means  by  which  nitrogen  is  furnished  to  plants  in  nature,  it  is 
most  important  to  consider  the  origin  of  nitric  acid. 

At  the  request  of  the  French  Government,  the  Academy  of 
Sciences  of  Paris,  in  »he  year  1770,  offered  a  prize  for  the  best 
treatise  on  the  formation  of  nitric  acid  and  its  production  in  arti- 
ficial nitre-beds.  The  judges  appointed  by  the  Academy,  includ- 
ing Lavoisier,  subjected  to  trial  70  treatises,  the  results  of  which, 
after  the  experience  of  50  years,  were  stated  in  a  small  work 
published  by  Gay  Lussac,  in  the  year  1825,*  in  the  following 
sentences : — 

1.  "  All  the  nitrogen  necessary  for  the  formation  of  nitric  acid 
is  yielded  to  it  by  animal  matter." 

2.  "Nitre  is   never   generated    from   the   air  in   substances 

•  Instruction  sur  la  fabrication  du  salpitre,  publii  par  la  Commi$$ion 
de»  poudres  et  salpitres,  1825 


FORMATION  OF  NITRE.  319 

adapted  for  its  formation,  without  the  co-operation  of  anima. 
matter." 

This  result  of  very  numerous  and  correct  experiments  contra- 
dicts completely  the  view  that  nitre  may  be  generated  in  mixtures 
of  earth  destitute  of  animal  matter,  and  therefore  at  the  expense 
of  the  constituents  of  the  air.  The  advocates  of  this  view  cite  in 
defence  of  it  the  following  experiments : — When  earth  forming 
nitre  is  freed  from  all  its  soluble  salts  by  lixiviation,  and  is  then 
exposed  for  several  years  to  the  action  of  the  air,  it  yields  a  se- 
cond crop  of  nitre,  and  these  crops  may  be  obtained  three  or  four 
times  in  succession,  although  in  different  proportions.  The  ad- 
vocates of  this  theory,  considering  that  all  the  substances  con- 
taining nitrogen  are  removed,  argue  that  the  nitrogen  of  the  nitre 
formed  afterwards,  must  have  been  derived  from  the  air.  But 
this  conclusion  is  opposed  to  all  rules  of  inductive  science.  When 
a  known  cause  produces  the  same  action  in  all  cases  submitted 
to  examination,  we  must  revert  to  the  same  cause  in  considering 
the  same  action  in  cases  not  examined  ;  for  we  have  no  right  to 
assign  to  it  a  new  cause,  in  order  to  save  us  the  trouble  of  a 
closer  investigation. 

The  advocates  of  the  opinion  that  the  nitrogen  of  the  air  is  con- 
verted into  nitric  acid  in  the  nitre-beds,  have  never  estimated  the 
amount  of  substances  containing  nitrogen  existing  in  those  beds ; 
and  they  have  never  compared  with  this  amount  the  quantity  of 
nitric  acid  actually  generated.  Those  who,  like  Gay  Lussac, 
have  taken  this  trouble,  found  that  the  quantity  of  nitric  acid 
formed  corresponded  to  the  quantity  of  animal  matters  present  in 
the  mixture ;  less  nitre  being  formed,  when  the  amount  of  the 
latter  was  decreased,  and  by  its  increase,  a  greater  quantity  of 
nitre  was  produced. 

Another  reason  for  the  opinion  was,  that  nitrates  were  formed 
in  certain  limestone  caverns  in  Ceylon,  where,  according  to  Dr. 
Davy,  nitrates  of  potash  and  lime  occur  in  a  limestone  containing 
felspar,  but  quite  destitute  of  animal  matter.  But  the  latter  as- 
sertion is  very  questionable,  as  there  is  scarcely  a  limestone  in 
existence  that  does  not  yield  ammoniacal  liquid  on  being  subjected 
to  distillation.  An  experiment  with  materials  expressly  prepared 
ibr  this  purpose  (carbonate  of  lime,  felspar,  and  water  free  from 


216  IS  NITRIC  ACID  FOOD  FOR  PLANTS  ? 

ammonia),  and  conducted  in  this  cavern,  in  order  to  see  whether 
nitric  acid  would  be  formed,  would  have  completely  decided  the 
qucetion,  if  nitric  acid  had  been  found  in  the  mixture  after  a  cer- 
tain  time  ;  but  this  experiment  was  not  made,  neither  was  the 
water  which  filtered  through  the  roof  of  the  cavern  subjected  to 
examination.  The  conclusion  that  nitric  acid  is  formed  in  these 
cases,  at  the  expense  of  the  nitrogen  of  the  air,  is  not  in  any  way 
confirmed — it  is  only  certain  that  the  cause  of  the  formation 
of  nitre  in  these  caves  remains  unknown  to  those  who  have  ex- 
amined them. 

It  often  happens  that  the  well-water  of  towns  contains  a  con- 
siderable quantity  of  nitre  which  does  not  exist  in  the  wells  and 
springs  outside  the  towns.  Berzelius  detected  nitrates  in  the  well- 
water  of  the  city  of  Stockholm.  Margraf  also  mentions  its  ex- 
istence ;  and  I,  myself,  have  shown  the  presence  of  nitrates  in 
the  waters  of  twelve  wells  in  the  town  of  Giessen,*  although  they 
could  not  be  detected  in  the  waters  of  six  wells  separated  2300 
paces  from  the  town.  Animal  matter,  in  a  state  of  decay  and 
putrefaction,  existed  abundantly  in  the  soil  in  all  the  places  where 
nitrates  were  found,  and  its  nitrogen  was  converted  into  ni- 
tric acid  wherever  the  conditions  for  this  conversion  were  found 
united. 

A  large  proportion  of  the  nitre  used  in  France,  for  the  manu- 
facture of  gunpowder  and  for  other  purposes,  is  obtained  at  Paris. 
The  manufacturers  of  nitre  use  in  its  preparation  the  lower  par's 
of  old  broken-up  houses,  which  have  been  in  constant  contact 
with  the  liquids  of  the  street.  Nitre  exists  in  large  quantity  in 
the  lower  parts  of  houses,  while  the  upper  parts  do  not  contain  a 
trace  of  it. 

It  cannot  be  denied  that  plants  grow  more  powerfully  and 
luxuriantly  in  a  soil  capable  of  forming  nitre,  than  they  do  in  a 
soil  unfit  for  its  formation. 

The  favorable  influence  of  such  a  soil  on  vegetation  is  justly 
ascribed  to  the  animal  matters  contained  in  it,  to  the  alkalies,  and 
to  the  phosphates  existing  in  the  animal  matter.  Out  of  the  ani- 
mal matter  also,  is  formed  the  ammonia  so  necessary  for  the  sup- 

•  Annates  de  Chimie  et  de  Physique,  vol.  xxxv.,  232. 


FORMATION  OF  NITRE.  2x1 

port  of  vegetation,  and  without  the  presence  of  wKich  nitric  acid 
could  not  be  formed.  ,.v       .  • 

The  presence  of  alkaline  nitrates  in  a  soil  indicates  with  the 
greatest  certainty,  that  the  most  important  conditions  for  the 
growth  of  plants  are  united  in  it ;  but  these  salts  are  not  the  pri- 
mary causes  of  the  growth,  because  both  the  formation  of  nitre, 
and  the  luxuriant  growth  of  plants,  are  effects  of  similar  causes 
acting  on  the  earth.  It  is  certain  that  the  vicinity  of  the  saltpetre 
mines  of  Quarta  Jaga  and  Santa  Rosa,  described  by  Darwin, 
although  saturated  with  nitrates,  forms  a  complete  waste,  in  which 
a  small  cactus  is  scarcely  able  to  grow.  The  cause  of  its  sterility 
may  be  the  want  of  rain  ;  but  if  it  were  moist,  and  obtained 
abundant  supplies  of  rain,  the  nitrates  would  have  disappeared 
long  since ;  and,  even  without  their  presence,  vegetation  would 
flourish  luxuriantly  in  this  climate. 

The  common  error  is  to  confound  a  soil,  in  which  nitrates 
EXIST,  with  one  in  which  they  are  in  the  act  of  forming.  If  the 
first  soil  be  Wanting  in  the  conditions  (animal  matter)  necessary 
for  a  further  formation  of  nitric  acid,  it  will  prove  sterile,  but 
will,  on  the  contrary,  be  fertile  if  these  conditions  exist.  The 
latter,  and  not  the  nitrates,  are  therefore  the  causes  of  the  better 
growth  of  vegetation. 

It  follows  from  the  preceding  observations,  that,  as  far  as  our 
experiments  extend,  the  formation  of  nitric  acid  on  the  surface  of 
the  earth,  is  dependent  on  the  presence  of  animal  matter. 

But  as  animal  substances  receive  their  nitrogen  from  the 
atmosphere  in  the  form  of  ammonia,  the  primary  origin  of  the 
nitric  acid  of  nitrates  must  be  the  ammonia  of  the  atmosphere. 
But  it  may  be  affirmed,  in  addition  to  this,  that  ammonia  is  not 
the  only  ultimate  source  of,  but  that  it  is  actually  the  immediate 
source  of  nitric  acid.  We  have  reason  to  believe  that  the  nitro- 
gen of  decaying  animal  substances  assumes  the  form  of  ammonia, 
before  being  converted  into  nitric  acid  ;  and  that  it  must  first  be 
in  the  state  of  ammonia,  before  it  is  able  to  form  nitric  acid  with 
the  oxygen  of  the  air.*  Hence  we  must  view  ammonia  as  the 
principal  source  of  the  formation  of  nitric  acid  on  the  surface  of 

•  See  the  Chapter  on  Eremacansi?  in  s*>-nnd  part  of  this  book. 

n 


318   •  IS  NITRIC  ACID  FOOD  FOR  PLANTS  ? 

the  earth  ;  and  we  may  expect  the  production  of  the  latter 
wherever  ammonia,  and  the  conditions  for  its  oxidation,  are 
found  united. 

The  occurrence  of  large  beds  of  nitrates  in  America  cannot 
afford  the  most  distant  reason  for  the  assumption  that  they  are 
formed  in  an  unusual  way  ;  it  is  unnecessary  to  call  in  the  as- 
sistance of  the  nitrogen  of  the  air,  in  order  to  explain  their  great 
extent.  We  find  in  nature  whole  mountains  consisting  of  shell- 
fish, and  of  remains  of  microscopical  animals,  which  must  have 
contained  a  certain  quantity  of  nitrogen  when  alive.  We  find 
also  large  layers  of  animal  excrements  (Coprolites),  which  place 
beyond  all  doubt  the  former  existence  of  innumerable  individuals 
of  species  now  extinct.  In  the  processes  of  decay  and  putrefac- 
tion to  which  they  have  been  subjected,  the  nitrogen  of  their 
bodies  could  have  escaped  only  in  two  forms  ;  in  cold  climates, 
it  would  assume  the  form  of  ammonia,  and  in  warmer  countries, 
the  form  of  nitric  acid,  which  must  accumulate  wherever  the 
salts  formed  by  means  of  it  are  not  carried  off  by  water. 

Ammonia,  however,  is  not  the  only  source  of  the  formation  of 
nitric  acid.  In  the  action  exerted  by  the  electric  spark  on  the 
constituents  of  air  (which  are  also  the  constituents  of  nitric  acid), 
we  recognise  a  second  source,  which,  to  all  appearance,  is  very 
extended. 

Cavendish  was  the  first  to  observe,  that  by  a  continued  passage 
of  electric  sparks  through  moist  air,  its  volume  diminished,  and 
an  acid,  soluble  in  water,  was  formed  at  the  same  time.  This 
great  philosopher  proved,  by  a  series  of  decisive  experiments, 
that  the  constituents  of  the  air,  the  nitrogen  and  oxygen,  united 
to  form  nitric  acid  when  exposed  to  the  influence  of  electricity. 

Now  it  is  probaole 'that  lightning  (the  most  powerful  electric 
spark  known),  in  its  passage  through  moist  air,  may  effect  a  com- 
bination of  the  constituents  of  air,  in  consequence  of  which  nitric 
acid  would  be  formed. 

In  an  examination  of  rain-water,  which  the  author  of  the 
present  work  undertook  in  the  years  1826-1827  (Annales  de 
Chimie  et  de  Physique,  xxxv.,  329),  it  was  actually  found  that 
out  of  seventy-seven  analyses  made  of  the  residue  of  rain-water, 
seventeen  of  them,   obtained  by  the  evaporation  of  the  rain  of 


FORMATION  OF  NITRIC  ACID.  219 

thunder-storms,  contained  more  or  less  nitric  acid,  partly  in  com- 
bination with  lime,  and  partly  with  ammonia.  In  the  sixty  others, 
only  two  contained  traces  of  nitric  acid. 

The  occurrence  of  nitric  acid  in  rain-water  as  nitrate  of 
ammonia,  renders  it  uncertain  whether  the  nitrogen  of  the  former 
was  obtained  from  the  atmospheric  air  itself,  or  from  the  ammonia 
existing  in  it,  in  the  state  of  a  gas.  Henry  observed  that  ammo- 
niacal  gas,  mixed  with  oxygen,  and  exposed  to  electric  sparks,  is 
likewise  converted  into  nitric  acid.  It  is  obvious,  that,  if  the 
rain  contains  carbonate  of  lime  mechanically  mixed  with  it  in  the 
form  of  dust,  the  nitrate  of  ammonia  also  present  will  be  con- 
verted during  evaporation  into  carbonate  of  ammonia,  which  will 
escape,  and  into  nitrate  of  lime,  which  remains  in  the  residue. 
The  quantity  of  nitric  acid  contained  in  the  rain  of  a  thunder- 
storm cannot  be  estimated.  Two  or  three  hundred  pounds  of 
filtered  rain-water  yield  only  a  few  grains  of  a  colored  residue, 
and  the  nitrates  contained  in  the  latter  form  only  a  fractional 
part  of  its  weight. 

The  analysis  of  the  water  of  springs  and  of  rivers  is  much 
better  adapted  to  give  us  a  clear  conception  of  the  quantity  of 
nitric  acid  formed  by  the  influence  of  electricity  in  the  atmo- 
sphere. If  we  suppose  the  nitric  acid  to  exist  in  water  in  a  free 
state,  as  it  is  a  volatile  acid,  it  must  escape  during  the  evapora- 
tion of  the  water  in  porcelain  vessels,  so  that  the  residue  will  not 
contain  a  trace  of  it,  if  the  bases  necessary  for  its  fixation  be 
deficient.  The  water  of  our  springs,  streams,  and  rivers,  is  rain- 
water, which,  if  nitric  acid  were  originally  present  in  it,  must 
now  contain  nitrates,  by  filtering  through  the  earth,  which  in- 
variably contains  lime  and  alkaline  bases. 

It  follows,  from  the  interesting  observations  made  by  Gobel,  in 
his  journey  to  Southern  Russia,  that,  by  the  evaporation  of  the 
river  Charysacha,  which  falls  into  the  lake  Elton,  the  latter  must 
receive  annually  47,777  millions  of  pounds  of  salts.  The  water 
of  the  Charysacha  contains  scarcely  5  per  cent,  of  salts  ;  so  some 
conception  may  be  formed  of  the  quantity  of  water  which  must 
evaporate,  in  order  to  furnish  the  above  quantity.  The  river  has 
its  source  about  forty  wersts  from  Lake  Elton,  and  obtains  its 
water  from  the  rain  and  snow  falUng  on  the  mountains. 


two  IS  NITRIC  ACID  FOOD  FOR  PLANTS  ? 

If  nitric  acid  be  a  constant  and  generally  appreciable  consti- 
tuent of  rain-water,  it  is  obvious  that  we  ought  to  find  sensible 
traces  of  it  in  the  mother  liquor  remaining  behind  after  the  crys- 
tallization of  the  salt.  But  Gobel  did  not  observe  the  presence 
of  nitrates  either  in  the  water  of  the  river  or  in  the  deposited 
salt. 

In  the  water  of  the  Artesian  Well*  of  Grenelle  ;  in  the  water 
of  the  Nile  ;t  in  that  of  the  Seine,  which  contains  carbonate  of 
ammonia  in  dry  seasons  ;  in  the  waters  of  the  Thames,  or  of  the 
Rhine,  no  one  has  yet  proved  the  presence  of  nitrates. 

We  may  assume,  from  these  facts,  that  the  nitric  acid  fur- 
nished to  the  earth  in  Europe,  by  means  of  rain,  is  extremely 
small  in  amount ;  so  that,  even  if  the  nitric  acid  formed  by  light- 
ning exercise  a  favorable  action  on  vegetation,  still  this  influence 
cannot  be  considered  as  a  source  of  the  nitrogen  of  plants.  When 
it  is  considered  that  the  number  of  thunder-storms  in  a  year  does 
not  amount  in  some  districts  to  above  twelve  on  an  average,  and 
in  many  to  only  eight,  it  must  be  obvious  from  this,  that  it  would 
be  quite  impossible  to  prove  the  presence  of  nitric  acid  in  the 
waters  of  rivers  or  of  springs. 

Under  the  tropics,  where  thunder-storms  are  much  more  fre- 
quent than  with  us,  we  might  suppose  that  the  quantity  of  nitric 

*  Payen  found  in  10,000  parts  of  this  water : — 

Carbonate  of  lime           -         .         -         .  6*80 

"              magnesia  -         -         -        -  1*42 

"              potash        -         -        -        -  2-96 

Sulphate  of  potash          -         -         -         -  120 

Chloride  of  potassium    -         -         -         -  1  09 

t  Regr|i  It  found  in  22  lbs.  of  water  of  the  Nile  : —    

Carbonate  of  lime           -         -        -        -  5*30 

"             magnesia    -         -         -        -  7*43 

Peroxide  of  iron    -----  053 

Chloride  of  sodium         -         -         -        -  4'77 

Sulphate  of  magnesia      -         -         -        -  0-53 

Silica 1-06 

Alumina         -         -         -        -        -         -  1'59 

Extractive  matter           -        -        -        -  0-53 

Carbonic  acid 1219 

33-93  Grammes    '' 


DOES  NOT  YIELD  NITROGEN  TO  PLANTS.  221 

acid  in  rain-water  would  be  appreciably  greater.  But  the  known 
examinations  of  the  spring  and  river  waters  of  those  regions  ; 
for  example,  of  the  waters  of  Paipa,  near  Tunga,  of  the  water  of 
the  Rio  Vinagre.  and  of  the  hot  mineral  springs  of  the  Cordilleras, 
the  analyses  of  which  were  instituted  by  Boussingault,  in  South 
America,  without  the  presence  of  nitrates  being  detected,  show 
that  there  is  no  foundation  for  the  opinion  that  a  sensibly  greater 
quantity  of  nitric  acid  is  generated  in  those  regions,  by  the  action 
of  lightning,  than  in  the  temperate  zones. 

It  follows,  from  the  preceding  observations,  that  nitric  acid,  or 
its  salts,  are  not  destined  by  nature  to  yield  nitrogen  to  plants. 
If  it  were  actually  the  case  that  nitric  acid  did  yield  to  plants 
their  nitrogen,  we  must  assume  that  this  source  was  accessible  to 
all  plants  without  distinction.  But  it  is  completely  excluded 
from  marine  plants  ;  and  even  in  the  case  of  the  terrestrial  plants 
of  the  temperate  and  cold  zones,  the  rare  occurrence  of  thunder- 
storms would  prevent  us  from  considering  that  any  appreciable 
quantity  of  their  nitrogen  could  arise  from  nitric  acid  generated 
by  the  action  of  lightning  on  the  constituents  of  air. 

But^  even  on  the  assumption  that  nitric  acid  does  take  a  de- 
cided part  in  vegetable  life,  ammonia  still  remains  as  the  ultioiate 
source  of  the  nitrogen  of  plants  ;  for,  as  far  as  oar  knowledge 
at  present  extends,  all  the  nitric  acid  on  the  surface  of  the  earth 
is  formed  by  the  eremacausis  of  ammonia,  and  it  is  not  impro- 
bable that  the  nitric  acid,  which  occurs  in  the  rain  of  thunder- 
storms, may  be  dependent  on  the  presence  of  the  same  body. 

Although  we  thus  trace  back  the  action  of  all  animal  and 
other  substances  containing  nitrogen,  to  the  only  compound  which 
furnishes  this  element  to  all  plants,  in  a  state  of  nature,  we  do 
not  of  course  mean  to  exclude  the  application  of  these  other 
matters  to  the  purposes  of  agriculture.  When  we  know  that 
woollen  rags,  horn,  and  hair,  in  the  progress  of  decay,  offer  a 
slow  but  continued  supply  of  ammonia,  it  follows,  that  we  may 
use  them  wherever  their  price,  in  comparison  with  the  advantage 
anticipated,  does  not  exclude  their  application. 

The  same  reasoning  holds  good  in  the  case  of  nitrates.  In 
these,  nitrogen  exists  in  another  form  than  that  of  ammonia. 
Nitric  acid,  or  rather  nitrous  acid,  is,  in  its  chemical  relations, 


222  IS  NITRIC  ACID  FOOD  FOR  PLANTS  ? 


exactly  opposed  to  ammonia ;  but  we  see,  that  in  the  organism 
of  plants,  carbonic  acid  and  water  suffer  decomposition,  although 
their  constituents  are  united  by  a  much  greater  power.  We 
have  considered  sulphuric  acid  as  a  source  of  sulphur.  Why, 
then,  should  not  nitric  acid  suffer  a  similar  decomposition  by  the 
same  causes ;  why  should  not  its  nitrogen,  like  the  carbon  or 
sulphur,  become  a  component  part  of  a  plant  ? 

By  strewing  nitrate  of  soda  over  fields,  a  greater  crop  has  been 
obtained,  particularly  on  grass  land.  Upon  corn-fields  and  on 
roots,  it  has  had  less  influence. 

It  is  not  yet  decided  to  what  constituent  of  the  salt  its  favorable 
influence  is  due. 

When  the  crops  of  hay  and  straw  obtained  with  this  manure 
by  Mr.  Gray,  of  Dilston,  and  Mr.  Hyett  (Journal  of  the  Royal 
Agricultural  Society),  are  expressed  with  regard  to  their  quantity 
of  nitrogen,  the  singular  result  is  obtained,  that  the  amount  of 
nitrogen  in  these  crops  amounts  to  double  the  quantity  of  that 
contained  in  the  nitrate  used  as  manure  ! 

Now,  when  it  is  remembered  that  the  crop  of  many  meadows 
is  rendered  a  half,  twice,  or  even  three  times  greater,  by  ma- 
nuring with  burnt  bones  or  with  wood  ashes — with  matters, 
therefore,  containing  no  nitrogen,  it  still  remains  doubtful 
whether  the  action  of  nitrate  of  soda  should  be  ascribed  to  its 
nitric  acid. 

A  number  of  plants,  such  as  Borago  officinalis,  Mesembryan- 
themum  crystallinum,  Apium  graveolens,  the  sun-flower,  and  to- 
bacco, contain  dissolved  in  their  juices  considerable  quantities  of 
nitre,  which  does  not  exist  in  other  plants  growing  on  the  same 
soil.  The  presence  of  a  nitrate  in  plants  permits  only  one  con- 
clusion— that  the  nitrogen  of  nitric  acid  is  not  employed  in  their 
organism  for  the  formation  of  compounds  containing  that  element, 
because,  if  it  were,  at  a  certain  period  of  the  life  of  the  plant,  it 
would  disappear  on  account  of  this  conversion. 

Whatever  be  the  case  in  this  respect,  nitrates  are  manures, 
which  do  not  replace  those  constituents  of  the  soil  which  are  re- 
moved in  the  crops.  Hence,  although  either  by  means  of  their 
acid,  or  of  their  alkalies,  the  rowth  of  plants  may  be  increased 
tor  one  or  two  years,  this  very  increase  must  cause  an  earlier 


NITROGEN  OF  ThE  AIR  IN  VEGETATION.  225r 

period  of  exhaustion   and   poverty  to  the  soil.     A  proper  and 
lasting  advantage  cannot  he  expected  from  the  use  of  nitrates. 


DOES  THE  NITROGEN   OF  THE   AIR  TAKE  PART  IN  VE- 
GETATION ? 

Priestley  and  Ingenhouss  assumed  that  plants  possess  the 
power  of  assimilating  the  nitrogen  of  the  air.  The  former  states 
that  a  specimen  of  EpiloUum  hirsutum  kept  under  a  glass  globe 
of  ten  inches  in  height,  and  of  one  inch  in  width,  absorbed  within 
a  month  f  of  the  air  contained  in  it. 

These  experiments  have  been  repeated  by  Saussure  with  every 
care  (Recherches,  p.  189),  both  in  pure  nitrogen  and  in  atmo- 
spheric air,  exactly  according  to  the  method  described  by  Priest- 
ley,  but  the  results  were  quite  the  reverse.  Saussure  observes, 
"  I  have  continued  the  experiments  for  a  long  time,  but  I  never 
could  detect  a  diminution  of  the  nitrogen.  The  same  was  the 
case  with  all  kinds  of  plants  which  I  submitted  to  the  same  expe- 
riment. Plants,  therefore,  do  not  sensibly  diminish  the  bulk  of 
the  air ;  and  these  experiments  are  confirmed  by  those  of  Wood- 
house  and  Sennebier." 

Hence,  we  have  not  any  direct  proof  for  the  opinion,  that  the 
nitrogen  of  the  air  is  converted  into  a  component  part  of  a  plant 
by  its  vital  processes.  In  the  present  state  of  our  knowledge, 
indirect  proofs  are  equally  wanting. 

Many  writers  on  agriculture  cite,  as  decisive  proofs  of  the 
assimilation  of  the  nitrogen  of  the  air  by  plants,  the  experiments 
of  Boussingault,  but  their  interpretation  in  favor  of  this  view  is 
not  supported  by  facts.  This  distinguished  philosopher  instituted 
a  number  of  experiments  in  order  to  decide  the  question  regard- 
ing the  origin  of  nitrogen  in  plants,  and  we  give  the  results  of 
these  experiments  in  his  own  words  (Ann.  de  Chimie  et  de  Phy- 
sique, LXix.)  : — 

"  I  believe  that  I  have  proved  by  numerous  experiments,  that 
the  nitrogen  of  a   rotation  of  plants  is  greater  and   often   much 


224  NITROGEN  OF  THE  AIR  IN  VEGETATION. 


greater  than  the  quantity  contained  in  the  manure.  This  excels 
arises  doubtless  from  the  air,  and  it  is  more  than  probable  that, 
in  this  case,  a  part  of  the  excess  of  nitrogen  is  taken  up  in  the 
form  of  nitrate  of  ammonia,  which  M.  Liebig  has  shown  to  exist 
as  a  frequent  constituent  of  the  rain  of  thunder-storms.  But 
before  this  can  be  assumed,  it  will  be  necessary  to  examine  the 
action  of  this  salt  on  vegetation.'' 

In  a  later  treatise  on  this  subject,  Boussingault  says  (Annales 
de  Chimie  et  de  Physique,  3  Serie,  t.  i.,  p.  240)  :— 

"  When  these  tables  are  examined,  it  follows  that  the  nitrogen 
in  the  plants  obtained  amounts  to  more  than  that  present  in  the 
manure.  I  assume,  as  a  general  proposition,  that  this  excessi 
arises  from  the  air.  But  in  what  way  and  manne"  '"^iis  ele- 
ment   IS   TAKEN    UP    BY   PLANTS,    I   AM   UNABLE    TO    STATE.        Thc^ 

nitrogen  may  be  taken  up  directly  as  a  gas,  or  dissolved  in  water, 
or,  what  is  possible,  and  as  some  philosophers  (Saussure  for  ex- 
ample) believe,  the  air  may  contain  an  infinitely  small  quantity 
of  ammonia." 

The  experiments  of  Boussingault  are,  therefore,  proofs  that 
the  nitrogen  of  cultivated  plants  is  not  obtained  from  manure 
alone,  but  that,  besides  this,  they  contain  an  excess  which  can 
only  be  derived  from  the  atmosphere.  That  the  nitrogen  of  wiid 
plants  must  be  derived  from  the  air  is  so  obvious,  that  it  requires 
neither  proof  nor  experiments. 

Boussingault  had  not  the  slightest  intention  of  making  his  ex- 
periments the  foundation  for  the  opinion  that  the  nitrogen  of  air 
'might  be  converted  into  parts  of  the  plant,  but  only  employed 
them  as  proofs  that  the  nitrogen  of  cultivated  plants  is  derived 
from  the  atmosphere. 


GIANT  SEA- WEED.  2tl 


GIANT  SEA. WEED. 

(From  Darwin's  Journal  of  the  Voyage  of  the  Beagle,  pp.  303,  304.) 

"  There  is  one  marine  production,  which  from  its  importance  is 
worthy  of  a  particular  history.  It  is  the  kelp  or  Fucus giganteus 
of  Solander.  This  plant  grows  on  every  rock  from  low.water 
mark  to  a  great  depth,  both  on  the  outer  coast  and  within  the 
channels.  I  believe,  during  the  voyage  of  the  Adventure  and 
the  Beagle,  not  one  rock  near  the  surface  was  discovered,  which 
was  not  buoyed  by  this  floating  weed.  The  good  service  it  thus 
affords  to  vessels  navigating  near  the  stormy  land  is  evident,  and 
it  certainly  has  saved  many  a  one  from  being  wrecked.  I 
know  few  things  more  surprising  than  to  see  this  plant  growing 
and  flourishing  amidst  (..ose  great  breakers  of  the  Western 
Ocean,  which  no  mass  of  rock,  let  it  be  ever  so  hard,  can  long 
resist.  The  stem  is  round,  slimy,  and  smooth,  and  seldom  has  a 
diameter  of  so  much  as  an  inch.  A  few  taken  together  are 
sufliciently  strong  to  support  the  weight  of  the  large  loose 
stones  to  which,  in  the  inland  channels,  they  grow  attached ; 
and  some  of  these  stones  are  so  heavy,  that,  when  drawn  to  the 
surface,  they  can  scarcely  be  lifted  into  a  boat  by  one  person. 

"  Captain  Cook,  in  his  second  voyage,  says,  that  at  Kerguelen 
Land, '  some  of  this  weed  is  of  a  most  enormous  length,  though 
the  stem  is  not  much  thicker  than  a  man's  thumb.  I  have 
mentioned,  that  upon  some  of  the  shoals  on  which  it  grows,  we 
did  not  strike  ground  with  a  line  of  twenty-four  fathoms.  The 
depth  of  water,  therefore,  must  have  been  greater.  And  as 
this  weed  does  not  grow  in  a  perpendicular  direction,  but 
makes  a  very  acute  angle  with  the  bottom,  and  much  of  it 
afterwards  spreads  many  fathoms  on  the  surface  of  the  sea,  I  am 
well  warranted  to  say  that  some  of  it  grows  to  the  length  of 
sixty  fathoms  and  upwards.'  Certainly,  at  the  Falkland  Islands, 
and  about  Terra  del  Fuego,  extensive  beds  frequently  spring  up 
from  ten  and  fifteen  fathom  water.  I  do  not  suppose  the  stem 
of  any  other  plant  attains  so  great  a  length  as  360  feet,  as  suted 
11* 


22(5  GIANT  SEA- WEED. 


by  Captain  Cook.  The  geographical  range  is  very  consider. 
able ;  it  is  found  from  the  extreme  southern  islets  near  Cape 
Horn,  as  far  north,  on  the  eastern  coast  (according  to  informa- 
tion given  me  by  Mr.  Stokes)  as  lat.  43° — and  on  the  western  it 
was  tolerably  abundant,  but  far  from  luxuriant,  at  Chiloe,  in 
lat.  42°.  It  may  possibly  extend  a  little  further  northward,  but 
is  soon  succeeded  by  different  species.  We  thus  have  a  range 
of  15°  in  latitude ;  and  as  Cook,  who  must  have  been  well  ac- 
quainted with  the  species,  found  it  at  Kerguelen  Land,  no  less 
than  140°  in  longitude. 

"  The  number  of  living  creatures,  of  all  orders,*  whose 
existence  intimately  depends  on  that  of  the  kelp,  is  wonderful. 
A  great  volume  might  be  written,  describing  the  inhabitants  of 
one  of  these  beds  of  sea-weeds.  Almost  every  leaf,  excepting 
those  that  float  on  the  surface,  is  so  thickly  incrusted  with  coral- 
lines as  to  be  of  a  white  color.  We  find  exquisitely  delicate 
structures,  some  inhabited  by  simple  hydro-like  polypi,  others  by 
more  organized  kinds,  and  beautiful  compound  Ascidiae.  On  the 
flat  surfaces  of  the  leaves,  various  patelliform  shells,  Trochi,  un- 
covered molluscs,  and  some  bivalves  are  attached.  Innumerable 
Crustacea  frequent  every  part  of  the  plant.  On  shaking  the 
great  entangled  roots,  a  pile  of  small  fish,  shells,  cuttle-fish, 
crabs  of  all  orders,  sea-eggs,  star-fish,  beautiful  Holuthurise 
(some  taking  the  external  form  of  the  nudi-branch  molluscs), 
Planariae,  and  crawling  nereidous  animals,  of  a  multitude  of 
forms,  all  fall  out  together. 

"  I  can  only  compare  these  great  aquatic  forests  of  the 
southern  atmosphere  with  the  terrestrial  ones  in  the  inter- 
tropical regions.  Yet,  if  the  latter  should  be  destroyed  in  any 
country,  I  do  not  believe  nearly  so  many  species  of  animals 
would  perish,  as,  under  similar  circumstances,  would  happen 
with  the  kelp.  Amidst  the  leaves  of  this  plant,  numerous 
species  of  fish  live,  which  nowhere  else  would  find  food  or 
shelter ;  with  their  destruction,  the  many  cormorants,  divers, 
and  other  fishing  birds,  the  otters,  seals,  and  porpoises,  would 
soon  perish  also ;  and  lastly  the  Fuegian  savage,  the  miserable 
lord  of  this  miserable  land,  would  redouble  his  cannibal  feast, 
decrease  in  numbers,  and  perhaps  cease  to  exist." 


APPENDIX, 


EXPERIMENTS  OF  WIEGMANN  AND  POLSTORF 


The  composition  of  the  artificial  soil  used  in  the 

experiments  of  Wieg 

mann  and  Polstorf,  on  the  organic  ingredients  of  Plants,  was  as  follows 

(Preischrift,  p.  9)  :— 

Qu>:-zy  smd 

861-26 

Sulphate  of  potash 

0-34 

Chloride  of  sodium      .... 

0  13 

Gypsum  (anhydrous) 

1-25 

Chalk  (elutriated)       .... 

.       1000 

Carbonate  of  magnesia  . 

500 

Peroxide  of  manganese 

2-50 

Peroxide  of  iron              .... 

1000 

Hydrated  alumina        .... 

.       1500 

Phosphate  of  lime           .... 

1560 

^               Acid  of  peat  with  potash*  . 

3-41 

"            "         soda  .... 

2-22 

"            "        ammonia 

.       10-29 

lime 

3-07 

"             *•         magnesia 

1-97 

"             "         peroxide  of  iron 

3-32 

alumina 

4-64 

Insoluble  acid  of  peat     .... 

5000 

*  This  salt  was  made  by  boiling  common  peat  with  weak  potash  ley,  and 
precipitating,  by  means  of  sulphuric  acid,  the  dark-colored  solution.  This 
precipitate  is  that  termed  Torfsaeure  (acid  of  peat),  in  the  above  analysis. 
The  salts  of  this  acid,  referred  to  in  the  analysis,  were  obtained  by  dissolv- 
ing this  acid  in  potash,  soda,  or  ammonia,  and  by  evapoiating  the  solutions; 
the  salts  of  magnesia,  lime,  peroxide  of  iron,  and  alumina,  were  obtained 
by  saturating  this  solution  with  their  respective  bases,  by  which  means 
double  decomposition  was  effected.  Humus  is  the  substance  remaining  by 
the  decay  of  animal  and  of  vegetable  matters,  which  are  seldom  absent  from 
a  soil.  This  was  replaced  by  the  acid  of  peat  in  the  experiments  of  Wieg- 
mann  and  Polstorf,  When  the  acid  of  peat  is  boiled  for  some  time  with 
water,  it  passes  into  an  insoluble  modification  denoted  above  as  insoluble 
acid  of  peat. 


22S  APPENDIX. 


The  following  experiments  were  instituted  in  pure  sand,  and  in  the 
artificial  soil : — 

VICIA  SATIVA. 
A. — In  Pure  Sand. 

The  vetches  attained  by  the  4th  of  July  a  height  of  ten  inches,  and 
seemed  disposed  to  put  out  blossoms.  On  the  6th  of  the  same  month, 
the  blossoms  unfolded  ;  and  on  the  11th  they  formed  small  pods,  which, 
however,  did  not  contain  seeds,  and  withered  away  by  the  16th.  Simi- 
lar plants,  which  had  already  begun  to  have  yellow  leaves  below,  were 
drawn  with  their  roots  out  of  the  sand,  the  roots  washed  with  distilled 
water,  and  then  dried  and  incinerated. 

B. — In  Ariijicial  Soil. 
The  plants  reached  the  height  of  eighteen  inches  by  the  middle  of 
June,  so  that  it  became  necessary  to  support  them  wiih  sticks ;  they 
blossomed  luxuriantly  on  the  16th  of  June  ;  and  about  the  26th  put  out, 
many  healthy  pods,  which  contained  on  the  8th  of  August  ripe  seeds, 
capable  of  germinating.  Similar  plants  to  the  above  were  taken  with 
their  roots  from  the  soil ;  they  were  then  washed  and  incinerated. 

HORDEUM  VULGARE. 
A. — Iji  Pure  Sand. 
The  barley  reached  on  the  25th  of  June,  when  it  blossomed  imperfectly, 
a  height  of  li  foot,  but  it  did  not  produce  seed  ;  and,  in  the  month  oi 
July,  the  points  of  the  leaves  became  yellow  ;  on  which  account,  on  the 
1st  of  August,  we  removed  the  plants  from  the  soil,  and  treated  them  as 
before. 

13. — In  Artificial  Soil. 

The  barley,  by  the  25th  of  June,  had  reached  a  height  of  2J  feet,  by 
which  time  it  had  blossomed  perfectly;  and  yielded,  on  the  10th  of 
August,  ripe  and  perfect  seeds ;  upon  which  the  plants,  together  with 
their  roots,  were  taken  from  the  soil,  and  treated  as  formerly. 

AVENA  SATIVA. 
A. — In  Pure  Sarul. 
The  oats,  on  the  30th  of  June,  were  \h  foot  in  height,  but  had  blos- 
somed very  imperfectly  ;  they  did  not  produce  fruit ;  and,  in  the  course 
of  July,  the  points  of  their  leaves  became  yellow,  as  in  the  case  of  the 
barley  ;  on  which  account  the  stalks  were  removed  from  the  soil  on  tlie 
l6t  of  August,  and  treated  as  formerly. 

B. — In  Artificial  Soil. 
The  oats  reached  2^  feet  on  the  28th  of  June,  having  blossomed  per- 


APPENDIX.  22d 


fectly.  By  the  16th  of  August  they  nad  produced  ripe  and  perfect 
seeds  ;  the  stalks  and  roots  were,  therefore,  removed  from  the  soil,  and 
treated  as  above. 

POLYGONUM  FAGOPYRUM. 
A. — In  Pure  Sand. 
The  buck-wheat,  on  the  8th  of  May,  seemed  to  flourish  the  best  of  all 
the  plants  grown  on  pure  sand.  By  the  end  of  June,  it  had  reached  a 
height  of  1  i  foot,  and  branched  out  considerably.  On  the  28th  of  June, 
it  began  to  blossom,  and  continued  to  blossom  till  September,  without 
producing  seeds.  It  would  certainly  have  continued  to  blossom  still 
longer,  had  we  not  removed  it  from  the  soil  on  the  4th  of  September,  as 
it  lost  too  many  leaves :  it  was  treated  as  before. 

B. — In  Artificial  Soil. 
The  buck-wheat  grew  very  qiiickly  in  this  soil,  and  reached  a  height 
of  2i  feet.  It  branched  out  so  strongly,  that  it  was  necessary  to  support 
it  with  a  stick;  it  began  to  blossom  on  the  15th  of  June,  and  produced 
perfect  seeds,  the  greater  number  of  which  were  ripe  on  the  12th  of 
August.  On  the  4th  of  September,  it  was  taken  from  the  soil  along 
with  the  roots,  and  treated  as  before,  on  account  of  losing  too  many 
leaves  from  below ;  although  it  was  partly  still  in  blossom,  and  with 
unripe  fruit. 

NICOTIANA  TABACUM. 
A. — In  Pnre  Sand. 
The  tobacco-plant  sown  on  the  10th  of  May  did  not  appear  till  the  2d 
of  June,  although  it  then  grew  in  the  normal  manner  ;  when  the  plants 
had  obtained  their  second  pair  of  leaves  I  removed  the  superfluous 
plants,  leaving  only  the  five  strongest  specimens.  These  continued  to 
grow  very  slowly  till  the  occurrence  of  frost  in  October,  and  obtained 
only  a  height  of  five  inches,  without  forming  a  stem.  They  were 
removed  along  with  their  roots  from  the  sand  on  the  21st  October,  and 
treated  as  the  above. 

B. — In  Artificial  Soil. 
Th^  tobacco  sown  on  the  10th  of  May  came  up  on  the  22d  of  the 
same  month,  and  grew  luxuriantly.  When  the  plants  obtained  the 
second  pair  of  leaves,  I  withdrew  the  superfluous  plants,  and  allowed 
only  the  three  strongest  to  remain.  These  obtained  stems  of  above 
three  feet  in  height,  with  many  leaves  ;  on  the  25th  of  July  they  began 
to  blossom ;  on  the  lOlh  of  August,  they  put  forth  seeds ;  and,  on  tht 


230 


APPENDIX. 


8th  of  September,  ripe  seed  capsules,  with  completely  ripe  seeds,  were 
obtained.  On  the  27th  of  October,  the  plants  were  removed  from  the 
soil,  and  treated  as  above. 

TRIFOLIUM  PRATENSE. 
A. — In  Pure  Sand. 
The  clover,  which  appeared  on  the  5th  of  May,  grew  at  first  pretty 
luxuriantly,  but  reached  a  height  of  only  3i  inches  by  the  I6th  of  Octo- 
ber, when  its  leaves  became  suddenly  brown,  in  consequence  of  which  I 
removed  it  from  the  soil,  and  treated  it  as  above. 

B. — In  Artificial  Soil. 
The  clover  reached  a  height  of  ten  inches  by  the  16th  of  October ;  it 
was  bushy,  and  its  color  was  dark  green.     It  was  taken  from  the  soil,  in 
order  to  compare  it  with  the  former  experiments,  and  was  treated  in  the 
same  way. 

CONSTITUKNTS    OF    THE    ASHES    OF   THE    SEED. 

100  parts  of  dry  seeds  yield — 


Soluble  in            Soluble  in 
water.              muriatic  acid. 
Viciafaba.         .         .         .  l-,502                 0563 
Hordeum  vulgare       .         .  0-746                0-563 
Avena  sativa      .         .         .  0  465                0  277 
Polygonum  fagopyrum        .  0823                0*547 
Trifolium  pratense     .         .  1-218                3-187 

Silica. 
0-442 
1423 
2122 
0-152 
0-2S2 

Ashes  in 
100  pirts. 
=     2-567 
=     2  432 
=     2-864 
=     1-5-22 
=     4-687 

CONSTITUENTS    ( 

OF   THE    ASHES    OF    THE 

PLANTS    GROWN    IN    PURE    SAND 

AND    IN   THE    ARTIFICIAL    SOIL. 

Soluble  in 
water. 

Soluble  in 
muriatic  acid 

Insoluble  in  water 
and  muriatic  acid 

'.Silica).           Ashes 

Vicia    sativa,  J 
15  grms.  plants, ) 
dried  in  air  .     .  j 

'  In  sand   .         .  0-516 
j  In  artificial  soil  0-693 

0  375 
0-821 

0-135 
0-3-20 

=     10'26 
=     1-834 

Hordeum  vul- 1 
gare,  125  grms. 
plants       ... 

Avena  sativa, 
13  grms.  plants, 

Polygonum 
fagopyrum    . 

^Sand        .         .  01-23 
[Soil          .         .  0-167 

0-195 
0-2-26 

0-355 
0-487 

=     0-673 
=     0  880 

iSand        .        .  0  216 
'  Soil          .         .  0-225 

0-0-24 
0-030 

0-094 
0-226 

0-354 
0-461 

0-045 
0-133 

=     0-594 
=     0-746 

=     0-225 
=     0-507 

Nicotiana 
tabacum  ..." 

'Sand(4grms.  K.200 
plants)      .     .^223 

1  Soil      12-5      I         g 
^plants)      .     .5^^*^ 

*Sand     .     .       .  0-522 
|Soil      .     •       .0  659 

0-252 
2-228 

0031 
0-549 

=     0-506 
=     3-923 

Trifolium      " 
pratense,     145 
grammes  plants ' 

0350 
0-943 

0-091 
0-082 

=     0-96S 
«     1-684 

APPENDIX. 


331 


The  preceding  numbers  express  the  unequal  weight  of  mineral  nutritive 
substances  taken  up  from  the  sand  and  artificial  soil  by  equal  weights 
of  the  different  plants  mentioned.  The  absolute  and  not  the  relative 
weight  of  the  component  parts  of  the  ashes  is  given.  For  example,  the 
live  tobacco  plants  grown  in  sand  gave  0*606  gr.  in  ashes,  whilst  the 
three  which  grew  in  the  artificial  soil  gave  3*923  ;  five  would,  therefore^ 
have  given  6*525  gr.  The  proportion  of  the  mineral  ingredients  taken 
up  by  five  tobacco  plants  from  the  sand,  and  that  taken  up  from  the  arti- 
ficial soil  by  an  equal  number  of  plants,  is  as  10:  120.  In  an  equal 
space  of  time,  those  whicii  grew  in  the  artificial  soil  absorbed  nearly 
thirteen  times  more  of  inorganic  ingredients  than  those  in  the  sand,  and 
the  whole  development  of  the  plant  was  exactly  in  proportion  to  the 
supply  of  food.  Wiegmann  and  Polstorf  subtracted  the  ashes  of  the 
seed  used  from  the  numbers  in  the  last  line,  which  show  the  amount  of 
ashes  in  a  given  weight  of  the  grown  plant^;  but  this  has  caused  a  small 
error  in  the  numbers,  as  all  the  plants  grown  in  the  sand  were  reduced 
to  ashes,  and  a  corresponding  amount  only  of  those  grown  in  the  arti' 
ficial  soil.  The  v/eight  of  the  seed  of  every  plant  grown  was  3  grammes 
if  we  except  the  tobacco,  which  was  not  weighed. 


TABLE 

Showing  the  Amount  of  Moisture  in  the  Vegetable  Substances  analysed 
in  the  Experiments  of  Boussingault. 


— 

Subst.  dried 
at  110"  C. 

Water. 

Subst.  dried 
at  llO''  C 

Water. 

Wheat.    .    .    . 

Rye 

Oats      .    .    .    . 
Wheat  straw    . 
Rye  straw    .    . 
Odt  suaw      .    . 
Poutoes    .    .    . 

0-855 
0-834 
0-792 
0-740 
0-813 
0713 
0-341 

i 
6666666, 

Beet 

Tnrnips  .... 
Helianthus  tub.  . 
Pcis    ... 
Pea  straw  . 
Clover  st'ilk     .    . 
SUilkofHel.tub. 

0-122 
0-075 
0-208 
0-914 
0-882 
0-790 
0-871 

0-878 
0-925 
0-792 
0-086 
0118 
0-210 
0-129 

COMPOSITION  OF  MANURE  DRIED  IN  VACUO  AT  110"  C 

Carbon. 

Hydrogen. 

Oxygen. 

Nitrogen. 

Salts  &  Earths. 

I. 

II. 
III. 
IV. 

V. 
VI. 

Mean. 

324 
325 

38-7 
36-4 
40-0 
345 

358 

3-8 
4-1 
45 
40 
43 
43 

4-2 

25-8 
26-0 

28-7 
191 
27-6 

27-7 

25-8 

1-7 
1-7 
1-7 
2-4 
2-4 
2-0 

2-0 

363 
357 
26-4 
38-1 
25-7 
315 

232 


APPENDIX. 


These  results  show  that  the  quantity  of  this  manure  necessary  for  one 
hectare  of  land  (4  Hessian  acres)  during  five  years  contains  ; — 


Carbon 

Hydrogen 

Oxygen 

Nitrogen 

Salts  and  earths 


Kilogrammes. 

3637-6 

426-8 

25-21-5 

203-2 

3271-9 


COMPOSITION  OF  THE  PRODUCE  OF  THE  LAND  DRIED  IN 
VACUO  AT  110^  C. 


With  the  Ashes. 

Without  the  Ashes.       ( 

1 

1 

1 

1 

1 

0) 

1 

e 

i 

g 

O 

^ 

o 

55 

< 

O 

» 

o 

iS 

Wheat    ... 

461 

5-8 

434 

23 

2-4 

472 

6-0 

44-4 

2-4 

Rye    .... 

46-2 

56 

442 

17 

23 

473 

57 

453 

1-7 

OiiLs    .... 

50-7 

6-4 

36-7 

2-2 

4-0 

52-9 

66 

38-2 

23 

Wheat  straw  . 

48-4 

53 

38-9 

0-4 

7-0 

52  1 

57 

41-8 

0-4 

Rye  straw   .    . 

49-9 

56 

40-6 

0-3 

36 

51-8 

5-8 

42-1 

0-3 

Gilt  straw    .    , 

5ifl 

5-4 

39-0 

0-4 

51 

52-8 

57 

411 

0-4 

Potatoes  .    .     . 

44-0 

5-8 

44-7 

1-5 

4-0 

45-9 

61 

46-4 

16 

Beet    .... 

42-8 

5-8 

434 

17 

63 

457 

6-2 

46-3 

1-8 

Turnips  .     .     . 

429 

55 

423 

1-7 

7-6 

46-3 

6-0 

45-9 

1-8 

Helianthus  tub. 

433 

5-8 

433 

1-6 

60 

460 

6-2 

461 

1-7 

Yellow  peas    . 

465 

6-2 

40-0 

42 

31 

480 

6-4 

413 

43 

Pea  straw    .     . 

45-8 

50 

3.5-6 

23 

113 

51-5 

5-6 

403 

2-6 

Red  clover  hay 

47-4 

50 

37-8 

21 

7-7 

513 

54 

411 

2-2 

Stalk  of  Hel.  tub 

457 

54 

45-7 

0-4 

2-8 

470 

5-6 

470 

04 

1.    ROTATION. 


Year. 

Substances. 

Produce 

of  a 
Hectare. 

Dry 
Produce 

Carbon. 

Hydrog.    Oxygen. 

SalU 
Nitrog.!    and 
Earths. 

2 

3 

4 

5 
Mant 

Potatoes    .    . 
Wheat.    .     . 
Wheat  straw 
Clover  (hay) 
Wheat .     .     . 
Wheat  straw 
Turnips    .    . 
Oats      .    .    . 
Oat  straw 

Total  .    . 
re  used  .    .    . 

Kilogr. 
12800 
1343 
3052 
5100 
1659 
3770 
9.'>50 
1344 
1800 

Kilopr. 
3085 
1148 
2258 
4029 
1418 
2790 
716 
1064 
1283 

Kilogr. 

1357-4 
5293 

10930 

1909-7 
653-8 

13.504 
307-2 
539-5 
642-8 

Kilogr. 

178  » 
66-t, 

119-7 

301-5 
82-2 

147-8 
393 
68-0 
693 

Kilogr. 

1379.0 
4982 
878-2 

15230 
6154 

1085-3 
302-9 
390-5 
500-4 

Kilogr.    Kilogr. 
46-3          1234 
264           27-5 
9-0    ;      158-1 
84-6   ^      3102 
32-6            340 
11-2          19.5-3 
12-2            54-4 
23-3            42-6 
51            65  4 

40418 
49086 

17791 
10161 

83831 
3637-6 

973-3   1     7172-9 
4268        2621-5 

250-7         1010-9 
303-2        3271^9 

Differ 

ence  .... 

+7630 

+47455 

+546  5   1 +4551-4 

+47-5    — 2261-0  i 

APPENDIX. 


5:^3 


2.  ROTATION. 


Produce 

Dry 

Salts 

Year. 

Substances. 

of  a 
Hectare. 

Produce 

Carbon. 

Hydrog. 

Oxygen. 

Nitrog. 

and 

Earths. 

Kilogr. 

Kilogr. 

Kilogr. 

Kilogr. 

Kilogr. 

Kilogr.  i  Kilogr.  | 

1 

Beet.    .    .    . 

26000 

3172 

1357-7 

1840 

1376  7 

539 

199-8 

2 

Wheat.    .    . 

1185 

1013 

4670 

58-8 

439-0 

233 

243 

Wheat  straw 

2693 

1993 

964-0 

105-6 

775-3 

8-0 

1395 

3 

Clover  .    .    . 

5100 

4029 

1909-7 

2015 

15230 

84-6 

3102 

4 

Wheat.    .     . 

1659 

1418 

653-8 

82-2 

615-4 

326 

34-0 

Wheat  straw 

3770 

2790 

1350-4 

147-8 

1085-3 

11-2 

195-3 

Turnips    .    . 

9550 

716 

307-2 

393 

302-9 

122 

54-4 

5 

Oiits      .    .    , 

1344 

1064 

539-5 

68-0 

390-5 

23  3 

426 

Oat  straw     . 
Total  .    . 

1800 

1283 

642-8 

693 

500-4 

51 

654 

53101 

17478 

8192-1 

956-5 

7009-1 

2542 

1005-5 

Manure  used  .    .    . 

49086 

10161 

3637-6 

4268 

26215 

2032 

3271-9 
—22064 

Diffen 

3nce   .... 

+7317 

+45545 

+529-7 

+4387-6 

+51-0 

3.  ROTATION. 


Produce 

Dry 

Salts 

Year. 

Substances. 

of  a 
Hectare. 

Produce. 

Carbon. 

Hydrog. 

Oxygen. 

Nitrog. 

and 
Earths. 

Kilogr. 

Kilogr. 

Kilogr. 

Kilopr. 

Kilogr. 

Kilogr. 

Kilogr. 

1 

Potatoes     . 

12800 

3085 

1357-4 

178-9 

13790 

46-3 

123-4 

2 

Wheat  .     . 

1343 

1148 

529-3 

66-6 

498-2 

26-4 

275 

Wh't  straw 

3052 

2-258 

1093-0 

119-7 

878-2 

9-0 

158-1 

3 

Clover  stiilk 

5100 

4029 

19097 

201-5 

15220 

84-6 

310-2 

4 

Wheat  .    . 

1059 

1418 

653-8 

82-2 

615-4 

32-6 

34-0 

Wh't  straw 

3770 

2790 

1.350-4 

147-8 

1085-3 

11-2 

1953 

Turnips      . 

9550 

716 

307-2 

39-3 

30-2-9 

122 

544 

5 

Peas.    .    . 

1092 

998 

464-1 

61-9 

399-2 

419 

30-9 

Pea  sUaw  . 

2790 

2461 

11273 

1230 

8761 

5(i-6 

2781 

6 

Rye  .    .    . 

1679 

1394 

644-0 

78-1 

616-1 

237 

.^2-1 

Rye  straw 
Total    . 

3731 

3033 

1513-5 

169-8 

1231-4 

9-1 

109-2 

46566 

23330 

10949-7 

1268-8 

9404-8 

3536 

1,353-2 

Manure  used    .    . 

58900 

12192 

43<)4-2 

5122 

3145-5 

243-8 

3925-8 

Differ 

ence    .    .    . 

+11138 

+05855 

+756-6 

+62593 

+109-8 

—2572-6 

4.  ROTATION. 


Year. 

Substances. 

Produce 

of  a 
Hectare. 

Dry 
Produce 

Carbon. 

Hydrog.    Oxygen. 

j 

Nitro. 

Salts 

and 

Earths. 

1 
3&3 

Mam 

Manured  fallow 
Wheat     .    .    . 
Wheat  straw   . 

Total  .    . 
ire  used     .    .    . 

Kilogr. 

3318 
7500 

Kilogr. 

2836 
5550 

Kilogr. 

1037-4 

2686-2 

Kilogr. 

164-5 
294-2 

Kilogr. 

1230-8 
21,59-0 

Kilogr 

65-2 
2-22 

Kilogr. 

68-1 

388-5 

10818 
20000 

8386 
4140 

3723-6 
14821 

458-7 
173-9 

33898 
1068-1 

87-4 
82-8 

456.6 
13331 

Differ 

ence 

1+4246 

+2241-5 

+284-8  +2321-7 

i 

+4-6 

-876-5 

23« 


APPENDIX. 


«-• 


If 


PI 


5;==      '^ 


Sc9    »:- 


•2    ^ 

■C      is 

I      I- 


<N 


I    2 


TABLE 

Of  the  Mineral  Constituents  put  on  a  Hectare  of  Land,  tn  the  Manure 

during  five  years,  in  Kilogrammes. 


— 

Total  weight. 

of 

the  ashes. 

Phosphoric 
Acid. 

i 

i 

•i 

1 

1. 
1-° 

P 

52 

Ashes  of  the  dung     .     . 

Composition  of  the  ix;at 

ashes 

3272       98 
5000         0 

62 
270 

30 
15 

281 
300 

118 

30 

SU     2333 
115     3275 

3U0 

185 

Sum 

8272       98 

332 

35 

581 

148  1    370  j  5508 

385 

APPENDIX. 


235 


COMPOSITION  OF  THE  ASHES  OF   PLANTS  GROWN  AT 
BECHELBRONN. 


e  a 

■  -\ 
hi 

Names  of  the 

i 

CB* 

^ 

?l 

Plants. 

r< 

m 

08 

■S 

c 

li 

O  a 

o 

. 

Ph 

o 

'^ 

•-J 

ft. 

(» 

'^ 

!  Pofcitoe3  .    .     . 

13-4 

71 

11-3 

2-7 

5-4 

1-8 

51-5 

trace 

56 

0-5 

0-7 

1  Rod  beet .     .     . 

161 

1-6 

60 

52 

4-4 

7-0 

390 

60 

80 

2-5 

4-2 

j  Swedish  turnip 

140 

10-9 

61 

2-9 

43 

10.9 

33-7 

41 

6-4 

12 

5-5 

Jerusalem  arti- 

chokes .     .     . 

110 

2-2 

108 

1-6 

1-8 

2-3 

44-5 

trace 

130 

52 

7-6 

Wheat  griin    . 

00 

10 

47-0 

trace 

15-9 

2-9 

29-5 

trace 

1-3 

00 

24 

Wheat  straw   . 

00 

10 

31 

00 

5-0 

8-5 

9-2 

03 

67-6 

10 

3-7 

0;it  prain      .     . 

1-7 

10 

149 

0-5 

7-7 

3-7 

12-9 

00 

533 

1-3 

30 

Ont  straw     .     . 

32 

41 

30 

4-7 

2-8 

8-3 

2-t-5 

44 

40-0 

21 

2-9 

Clover.    .    .    . 

250 

2  5 

63 

2-6 

63 

24-6 

26(> 

0-5 

53 

03 

00 

Peas     .... 

0-5 

4-7 

301 

1-1 

11-9 

101 

353 

25 

1-5 

trace 

2-3 

French  beans   . 

33 

1-3 

26-8 

01 

11-5 

5-8 

491 

00 

10 

trace 

11 

Common  beans 

10 

1-6 

342 

0-7 

8-6 

51 

45.. 

00 

0-5 

trace 

3-1 

(Boussingault,  Economie  Rurale,  p.  327.) 


TABLE  OF  THE  MINERAL   CONSTITUENTS,  OR  ASHES,  GIVEN 
TO  A  FIELD  AND  REMOVED  FROM  IT. 


ill 

—  ^  2 

S 

•a 

Mean  produce  on  one  hec- 

S-i 

V 

S 

s,- 

tire  of  land=  10,000 

■l^ 

2^ 

c 

?'. 

.CS 

square  metres. 

mer 
stitu 
the 

t<= 

1 

a 

.H- 

<■ 

!U 

02 

O 

H^ 

S 

^ 

in 

Isi  planting: 

Potatoes 

123-4 

139 

8-8 

33 

22 

6-7 

63-5 

6-9 

m 

In  the  2<l  and  4th  years : 

g 

Wheat  grain    .     .     . 

550 

25-8 

0-6 

0-0 

16 

8-8 

16-2 

0-8 

E 

Wheat  straw  .     .     . 

390-6 

120 

40 

2-4 

33-2 

19-6 

37-2 

264-0 

^'^ 

In  the  3d  year  : 

^ 

Clover     

310-2 

195 

7-7 

81 

76-3 

19-5 

84-1 

16-4 

^ 

In  the  5th  year : 

O  It  grain     .... 

42-6 

6-4 

0-4 

0-2 

1-6 

3-3 

5  5 

22-7 

Oat  straw    .... 

654 

T9 

27 

30 

54 

1-8 

189 

26-2 

Turnips  (half  crop)  . 

544 

33 

5-9 

1-6 

5-9 

2-3 

20-6 

35 

1010-9 

82-8 

30-1 

18-6 

126-2 

62-0 

246-0 

340-5 

Ashes  of  the  manure*  . 

82720 

980 

332-0 

350 

581-0 

1480 

370-0 

55080 

Excess  above  amount  > 
of  ashes  in  the  crop   .  J 

72011 

15-2 

301-9 

10-4 

454-8 

86-t) 

1240 

5167-5 

(Boussingault,  Economie  Rurale,  p.  Si 4,  n.  336.) 

Consisting  of  dung  and  peat  -ashes,  the  ashes  of  which  bore  to  each  other 
the  relation  expressed  in  the  following  table. 


a36 


APPENDIX. 


TABLE 

Of  the  Mineral  Constituents  added  to  and  removed  from  the  Soil  in  thk 
Cultivation  of  Helianthus  tuberosus.     {Topinambour.) 


is 

11 

u 

s 

m 

4> 

C 

1 

6 

a 

13 

i 

II 

i 

02 

Ashes  of  the  tultt-m  raised  . 
in  the  1st  and  2d  years*  ' 
Ashes  of  the  dung  .    .    . 
Peat  ashes 

Sum  of  the  ashes  of  the 
manure 

Excess 

6600 

30290 
5000-0 

712 
910 
0 

146 

57-6 
2700 

10-6 

18-2 
150 

15-2 

2605 
3000 

11-8    293-6 
1090    236-2 
30-0  !  115-0 

85-8 

20110 
32750 

80290 

910 

3270 

332 

1            1 
560-5  11390  1351-3 

5286-0 

73690 

198 

3130 

226 

5453 

127-2 

577 

52000 

(Boussingault,  Economic  Rurale,  p.  336.) 

*  The  woody  and  other  parts  of  the  plant  were  burned  on  the  -spot,  and 
thus  left  to  the  soil. 


Hat/  grown  in  Meadows,  watered  by  the  Sauer,  near  Biirrenbach,  in  tw» 
crops  (1841  to  1842)  yielded  6  to  6'2  per  cent,  of  ashes  of  the  following 
composition : — 


I. 

II. 

III. 

Average. 

Cirbonic  acid 

Phos|)horic  acid    .... 

Sulphuric  acid 

Chlorine 

Lime 

Miignesia 

90 
53 
24 
23 

20-4 
60 

161 
1-2 

337 

55 
53 

2-9 
2-8 

15-4 
8-3 

273 
2-3 

29-2 
0-6 
0-4 

5-5 

= 

0-5 

— 

7-3 
54 

2-7 
2-6 

17-9 
7-2 

21-7 
1-8 

31-5 
0-9 
10 

Soda 

Silica 

Oxide  of  Iron    •    .    .         . 
IiOSS 

100 

100 

100 

100 

APPENDIX. 


237 


\f  the  annual  produce  of  hay  he  estimated  on  the  average  at  400  kilo- 
grammes  per  hectare,  then  along  with  it  there  must  be  removed  in  the 
crop,  from  the  same  surface,  244  kilogrammes  of  ashes,  consisting  of  ■ 

Kilogrammes. 
Carbonic  acid         .  .  .  .     178 

Phosphoric  acid  .  .  .  13*2 

Sulphuric  acid        .  .  .  .66 

Chlorine  ....  6-3 

Lime  .....     43"7 

Magnesia         ....  17*6 

Potash  and  Soda     ....     57-3 
Silica  .....  76-9 

Oxide  of  iron  .  .  .  .4*6 


2440 


(Boussingault,  Economie  Rurale,  pp.  339 — 340.) 


COMPOSITION  OF  A  STABLE  MANURE. 

ACCORDING   TO   THE    ANALYSIS   OF   RICHARDSOIir 

The  fresh  Manure  contained  : 

.     64-96 


Water 


Organic  matters 

Ashes        .             .             .             .             . 

24-71 

10-33 

100-00 

The  Manure  dried  at  212*  contained  :— 

Carbon      .             .             .             .             . 

37  40 

Hydrogen       .... 

5-27 

Oxygen     .            .            .            .            . 

25-52 

Nitrogen        .... 

1-76 

Ashes        ... 

3005 

100-00 

The  Asnes  contained : 

I.  Soluble  in  Water: 

Potash       .... 

322 

Soda 

2-73 

Lime         .... 

0-34 

Magnesia       .... 

0-26 

Sulphuric  acid     . 

3-27 

Chlorine        .... 

3-15 

Silica        ..... 

0-04 

II.  Soluble  in  Hydrochloric  acid  : 

Silica        .             .             .             .             . 

27-01 

Phosphate  of  lime      . 

7-11 

"              magnesia    . 

2-26 

*•              peroxide  of  iron 

4-68 

Carbonate  of  lime 

9-34 

"               magnesia 

1-63 

III.     Sand  (30-99),  Charcoal  (0-83) 

and  Loss  (3  14)      , 

34-96 

10000 


23S 


APPENDIX. 


■*^ 

o 
CO    "S 


90JBJ0J 


or   o    M    o       »ft 
■r  ^    »:-    C5      t- 

M    M     W     f-<         C< 


•AVBJJg  Tiaj 


T 

•AVBJJS  TJOJ 


'suBag  piaij 

JO  MT3JJg 


•OODEqOJ, 

jaAOUB}j 


•oosBqoj, 

■BUBAKH 


■fOAtiaq  aui  J 


•soABa^  Jij[ 


•j[JBa  iU 


'POOAV  -ti  J 


-pooMqasag 


rH    t-        CO 


T)<  >h  Tt<  o  do        if- 


eo  to  (N 


E  ?  5;  S      8  S?    ^. 

-<  -H   OS   -^         o  -^      r- 


8  ?3  «s    p?    §8  t^     « 

M    PJ    do        (O        00  O 


5  8  S  S  ^ 

6  «b  ■*  Ai  e» 


?§^ 


SSSS8SI2      i;; 

O    »h    «    d<    rH    i^  M 


3;  «b  «  ©  o  o        6* 


•     ...     .     -i     . 

^ I     '%^ 

ill  •-  -I  -.^iall  • 

.o^o,|o.g^gjSggSgS 

B     «    SO    3   =    «!   tg   ^   ^   JS   43   J3   a 


APPENDIX.  239 


ANALYSIS  OF  THE  ASHES  OF  THE  STRAW  OF  RYE,  BY 
DR.  FRESENIUS. 

A. — Ingredients  soluble  in  water  and  muriatic  acid. 

Potash  united  to  silicic  acid       *             .             .             .  .     6*88 

Sulphate  of  potash  .             .             .             .             .             .  1  -75 

Chloride  of  potassium     .....  0'25 

Chloride  of  sodium               .             .             .             .             .  0*56 

Lime  united  to  silicic  acid         .....     4*19 

Magnesia      .             .             .            ,             ,             .             .  0*76 

Phosphate  of  lime          .             .             .             .             .  .     2'50 

Phosphate  of  magnesia         .             .            .             .             .  1-28 

Phosphate  of  oxide  of  iron         .             .             .             .  .1*57 

Small  quantity  of  phosphate  of  protox.  of  manganese.       19*74 


B. — Residue  insoluble  in  water  and  muriatic  aetd. 

Potash  united  to  silicic  acid       .....     9'21 

Lime  united  to  silicic  acid  .  .  .  .  3-43 

Magnesia  united  to  silicic  acid  .  .  .  .  .     1'16 

Phosphate  of  iron     .  .  .  .  .  .  1-63 

Phosphate  of  protoxide  of  manganese   ....  traces 

Silicic  acid  .......  63-89 

Carbonaceoous  matter    .....    0'94 


SO-26 


10000 


Soluble  and  insoluble  together. 

Potash  united  to  silicic  acid       .....  16'69 

Sulphate  of  potash  ......  1*75 

Chloride  of  potassium    ......  0*25 

Chloride  of  sodium  .             .             .            .            .            .  0  56 

Lime  united  to  silicic  acid                                  .             .             .  7'62 

Magnesia      ....                         .             .  1*92 

Phosphate  of  lime         ......  2'50 

Phosphate  of  magnesia         ....             .  1-2S 

Phosphate  of  oxide  of  iron        .....  3-20 

Small  quantity  of  phosphate  of  protoxide  of  manganese. 

Silicic  acid               .             .             .            .            .             .  63*89 

Carbonaceous  matter    .            .            .            .            .             .  0*94 


10000 


ud 


APPENDIX. 


•jooH  oooaqo^x. 


•AlBJig  aojBjoj 


•aiaj  auiqa 


•AVBJjg  j«aqM 


'IBoajBiio  au{j 


•pooM  'aPlV 


•lunJiSTJiibnis 


•japia  paujaq 
-p»a  J"  [>ooM 


•pc)OA\ 
Xajaqo  qaiKqoj^f 


•poo^VV  siinq 


HJBa  '^^i^ 


•pooM  5(Bo 


•qaaaa 
pan  JO  iB03JBq3 


•qoaag  ajiHAV 
JO  inoaiKqo 


•qoaaa 
a»RMJopooAV 


Ml-        O  « 8  5J 

^  h-       oodo         Ah 


f?  O  OD  (»  t- »^  t- 


"?"     99 


300   o  CTOoo     y/i     iflo 


ifl  o  C5  «  »  « 


db  jj     «bo 


©  t-  O  ff<  Ifl  !0 


©©     ©o©  ©   o 


©«XX©iflQO 


00 »»      ^SSxS    « 

2g    g;''--^  S 


S    "3' 


S    S 


Q<p©(p  00-4^ 

pj©ioaji>rtPj 


^1 


■1:= 


5  a  w  *  « 


:-Sl-2 


8^ 


••5  -2 


li 


APPENDIX. 


241 


•pooA\ 


u?  m  O  O     •'5 

>A      r>o  *  o  c?    « 
lorj      "-<  o 


S  00  •*  i-HQO  S  I 


*pooA\  a^Jl'-wvog 


•pooA\  n^MH 


VK) 
i«lOHJopooA\ 


sii3i&at)ja  pooA\ 


•pooAV 


•5  s  « 

III 


e  -s     ©  «  ci  o    »P 


on 


•-<  1— I  l/S  tt"  O  CK' 
00  00  O  CTr»<  I-- 

»h  <j»  ih  do  c<  Tj* 


O-^f       o       o 


OO        OMO        C<0 


OO 


S;:!''^' 


-jnuiBAAJopooM 


11 


•g*^g' 


:ei 


"-"  o  e  "5  c3  ^  "^  .S  *  S 

x&iOQo6fiLiis3l^d< 


ANALYSES  OF  ASHES  BY  BERTHIER. 


Fern. 

Wheat 

Straw. 

Share 

Grass. 

Heath. 

Rhine 
Fern. 

Sulphate  of  potash  .... 

070 

0-4 

120 

50 

33 

Chloride  of  potassium 

Uace. 

32 

114 

1-2 

9-0 

Carbonate  of  potash 

trace. 

6-8 

16-7 

Potash  with  silica  . 

130 

Silica 

730 

71-5 

.w-a 

37-5 

16-5 

Carbonate  of  lime 

24-8 

9-6 

(i2 

280 

434 

Sulphate  of  lime 

14-4 

Phosphate  of  lime 

10 

23 

.  2-2 

1^0 

10^ 

Magnesia    •    .    . 

0.^ 

30 

1-0 

OiJ 

Oxide  of  iron  .    . 

1-4 

0-7 

Oxide  of  manganese 

61 

0-2 

.     1000 

1000 

1000 

1000 

1000 

12 


•43 


APPENDIX. 


DE  SAUSSURE'S  INQUIRIES  INTO  THE  ORIGIN  OF  THE 
MINERAL  INGREDIENTS. 


Granite  frorn 
Mount 
Breven. 


Stone  of  the 
La  Salle  Mount. 


Limestone. 

of  Reculey  de 

Thoiry. 


Lime 

Alumina 

Silica 

Oxide  of  iron  and  manga- 
nese   

Carbonic  acid 

Petroleum 

Loss 


1-74 
1325 
73-25 


2-76 


24-36— (Carbonate.) 

30- 

13- 

27- 

1-64 


9-8 
0625 


025 
0-5 


According  to  De  Saussure,  the  proportion  of  water,  carbon,  and  ashes 
in  the  plants,  of  these  three  mountains  is  as  follows  : 


100  parts  fresh 

1 

branches  with 
leaves  lost  by  dry- 

And give,  of 

ing  in  the  air. 

Water.           \ 

Carbon. 

Ashes. 

A. 

B.         '' 

A. 

B. 

A. 

B. 

Pine    .... 

5117 

48-24 

10-62 

11-11 

1-187 

1-128 

L-arch.     .    .     . 

5807 

5713 

10-16 

10-39 

0-961 

0-926 

Oleander     .    . 

59-73 

52-78 

9-05 

962 

0-654 

0-339 

Bilberry  .    .    . 

50-11 

47-60  : 

11-69 

12-32 

1-096 

1-048 

Juniper  .    .    . 

55-19 

40-00   1 

10-63 

11-46 

1-081 

1-082 

100  Ashes  contain 

Bilberry. 

Pine. 

a 

c 

a 

b 

e 

Carbonate  of  potash    •    •    •  i 

J      3-60 
4-24 

7-36  , 

Sulphate  of  potash  .    .    .    . ' 

).   16-38 

23-50  - 

12*63  i 

►     15 

Chloride  of  potassium      .     . 

• 

Carbonate  of  lime    .... 

40-35 

53-70 

46-34 

51-19 

63 

Carbonate  of  magnesia    .     . 

5-85 

6-77 

Alumina 

17-54 

1425 

14-o6 

11-95 

16 

Silica 

13-45 

175 

13-49 

6-87 

Oxide   of  iron  and  man-  ) 
ganese    J 

■ 

6-43 

6-80 

10-52 

10-00 

3 

10000 

100-00 

99-82 

100-00 

97 

APPENDIX. 


243 


Oleander. 

Juniper. 

a              b              c 

a               c 

Carb.  sulph.  and  chloride  of  pot.   . 

Carbonate  of  lime 

Carbonate  of  magnesia 

Alumina 

Silica 

Oxide  of  iron  and  manganese    .    . 

10-82 
30-02 

500 
28-80 
14-86 

8-40 

12-25 

57-00 

13-31 
5-44 
1100 

17-76 
71-54 

593 

4-8G 

15-25 
64-25 

0-53 

140 
66-6 

97-90 

9900 

10009 

100  Parts  of  the  Ashes  of  the  Humus  on  which  those  Plants  grew,  gave—' 


Earth  of 
Pine. 

Earth  of 
Oleander. 

Erirlh  of 
Juniper. 

a              c 

c 

c 

Salts  of  potash 

Carbonate  of  lime 

Carbonate  of  magnesia  .... 

Alumina 

Silica 

1-16 

0-37 

14-00 

60-50 

16-00 

4.57 
23-20 

37-10 
1310 
1610 

1-85 
10-65 

43-70 
14-27 
23-83 

13-0 

Oxide  of  iron  and  manganese    . 

92-03   1     94-68 

100-30 

244  APPENDIX. 


ANALYSES  OF  THE  ASHES  OF  SOME  PLANTS, 

BY   DE    SAUSSURE. 
CHEMICAL    INQUIRIES    INTO    VEGETATION.       LEIPZIG,    1805. 


The  method  of  analysis  employed  by  De  Saussure  consisted  of  the 
following  : 

A.  The  ashes  were  treated  with  water,  and  the  parts  soluble  in  it  were 
introduced  into. the  calculations,  in  the  second  and  following  columns. 

B.  The  residue  remaining  undissolved  in  the  last  operation  was  dis- 
solved in  nitric  acid,  and  evaporated  to  dryness ;  the  portion  now  insolu- 
ble in  water  was  silica. 

C.  By  precipitating  the  solution  obtained  in  B,  with  prussiate  of  pot- 
ash, the  iron  and  manganese  were  obtained,  the  amount  of  iron  supplied 
by  the  re-agent  being  subtracted  in  the  calculation. 

D.  By  a  further  precipitation  of  the  solution  with  ammonia,  the  earthy 
phosphates  were  obtained  (lime  and  magnesia). 

E.  By  treating  this  precipitate  with  caustic  potash,  neutralizing  it 
with  an  acid,  and  precipitating  it  with  ammonia,  the  earthy  phosphates 
mixed  with  alumina  (phosphate)  were  procured. 

F.  By  a  further  precipitation  of  the  liquid  D  with  carbonate  of  soda, 
and,  by  continued  boiling,  the  earthy  carbonates  were  obtained. 

G.  The  difference  of  the  products  of  these  different  operations,  when 
compared  with  the  total  weight  of  the  ashes  analysed,  expressed  the  few 
per  cent,  loss  ;  and  the  quantity  of  salts  with  alkaline  bases  which  were 
not  dissolved  by  the  first  treatment  with  water. 

According  to  the  second  mode  of  procedure,  which  Saussure  considers 
to  be  the  most  exact,  the  ashes,  containing  alkaline  phosphates,  were 
chiefly  analysed. 

The  ashes  were  dissolved  in  nitric  acid,  the  lime  and  magnesia  sepa- 
rated as  phosphates,  the  liquor  evaporated  to  dryness,  and  heated  to  red- 
ness with  the  addition  of  charcoal. 

The  residual  salts  were  now  saturated  with  acetic  acid,  dried  and 
treated  with  alcohol  ;  the  phosphates  and  sulphates  of  potash,  and  chloride 
of  potassium,  were  left  behind. 


APPENDIX.  245 


b.  The  residue  was  taken  up  by  water,  and  mixed  with  acetate  of 
.ime  ;  the  residue  being  dried  and  heated  to  redness,  was  treated  with 
acetic  acid  (c),  and  the  portio.i  not  dissolved  was  estimated  as  pure 
phosphate  of  lime,  of  which  it  was  assumed  that  100  parts  corresponded 
to  129  parts  phosphate  of  potash  ;  for  8  Ca  O  +  3  Pa  O^  gives  3  (Pj  O5, 
3K0). 

The  solutions  a  and  c,  and  also  that  remaining  after  the  precipitation 
with  acetate  of  lime,  were  evaporated  and  heated  to  redness ;  the  residue 
was  weighed,  and  the  chlorine  and  sulphuric  acid  estimated,  and  calcu- 
lated as  chloride  of  potassium  and  sulphate  of  potash.  By  subtracting 
the  two  latter  salts,  and  also  the  potash  calculated  from  the  phosphate 
of  lime,  from  the  weight  of  the  whole  residue,  the  quantity  of  potash  not 
existing  as  phosphate  of  potash  was  obtained. 

^either  of  these  two  methods  can  be  considered  accurate  in  the 
present  day.  But  as  all  the  analyses  were  executed  according  to  similar 
methods,  the  results  are  always  of  value,  in  so  far  as  they  are,  to  a  cer- 
tain extent,  comparable  with  each  other. 


246 


APPENDIX. 


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APPENDIX. 


247 


ANALYSES  OF  THE  ASHES  OF  PLANTS, 

BY   DE    SAUSSURE. 


100  Parts  Ashes 

contain 

...  1 

Name  of  Plant. 

lit 

It 

ICO  parts  of  A«he 
give  Soluble  Salts 

Us 

IP 
111 

'SI" 
IS 

£3 

II 

c 

6 

1 

Oak  leaves  10th  May 

53- 

72-24 

24- 

0-64 

012 

3- 

47- 

"    27th  Sept 

r)5- 

425 

18-25 

1-75 

23- 

14-5 

17- 

"    peeled  branches 

4- 

58-58 

28-25 

1- 

1225 

012 

26- 

"    the  bark  of  above 

60- 

29-75 

4-5 

1-75 

63-25 

0-25 

7- 

"    wood  of  same    . 

2- 

59-25 

4-5 

225 

32- 

2* 

386 

"    sap  of  same    .    . 

4- 

55-3 

24- 

2- 

ir 

7-5 

32- 

"    bark  of  same.    . 

CO- 

28-5 

3- 

2- 

66- 

1-5 

7- 

"    inner  bark  of  some 

TS- 

29-75 

3-75 

1- 

65- 

0-5 

7- 

"    e.xtract  of  the  woo( 

61- 

51- 

Oakwood,  mould   .    . 

41- 

32-5 

10-5 

14- 

10- 

32- 

Aqueous  extract  of  the 
mould 

111- 

66- 

Leaves  of  the  Populus 
nigra,  2<Uh  May    .  \ 

f)6- 

51-5 

13- 

1-25 

29- 

5- 

36- 

100  Parts  Ashes 

contain 

'S^ 

IS 

'S 

Name  of  Plant. 

kalies  an 
s  with  al 
ne  bases 

IS 

1.1 

11 

si    - 

II 

1 

^e. 

^1 

II 

6 

S4 

Leaves  of  the  Poplar] 

(Populus  nigra)  12th  \ 
Stem  of  the  Poplar    .    . 

93- 

44- 

'*' 

1-5 

36- 

'•5 

26- 

8- 

50-5 

16-75 

1-5 

27- 

3-3 

20- 

Bark  of  the  same  .     .     . 

72- 

29-2 

5-3 

1-5 

60- 

4- 

6- 

Leaves  of  the  Hazel- "l 

nut    (CoryluM    ^vel-  > 

61- 

50-7 

32-3 

1-5 

22- 

2-5 

28- 

lima),  1st  May     .        J 

Ditto,  22d  June      .    .    . 

62- 

30- 

19-5 

2- 

33-1 

4- 

22-7 

"      20th  Sept.    .    .    . 

70- 

44- 

14- 

1-5 

29- 

113 

11- 

Peeled  branches    .    .    . 

5- 

28- 

12- 

2- 

36- 

22- 

24-5 

Bark  of  same    .    .    .    . 

62- 

56-7 

35- 

012 

8- 

0-25 

12-5 

348 


APPENDIX. 


ANALYSES  OF  THE  ASHES  OF  PLANTS, 

B"V    DE    SAUSSURE. 


100  Parts  Ashes  contain 

|| 

J. 

"o   . 

.2.2 

iS 

c 

-'< 

Name  of  plant. 

c^ 

Si; 

■^r^ 

1-5  £ 

4;  2 

K  3 

SS 

^  = 

^■s 

iM 

Jw 

'£ 

IS. 

<5 

25 

« 

Il 

Wood  of  Moms  nigri    .    . 

7 

41-38 

2-25 

0-2 

56- 

0-12 

21- 

Soft  wood  of  the  same  .    . 

13- 

47-5 

27-25 

02 

24- 

1 

36- 

Bark  of  the  same  .... 

8a- 

30-13 

8-5 

1-1 

45- 

1525 

7- 

Inner  part  of  the  bark  .     . 

8d- 

:34-38 

16-5 

1- 

43- 

0-13 

10- 

Wood  of  the  white  beech, 

Carpinus  betuhis     .     . 

fi- 

48-63 

23- 

225 

26- 

012 

22- 

Sap  of  same 

7- 

47- 

36- 

1- 

].r 

1- 

18- 

Bark  of  same 

134- 

34-88 

4-5 

012 

59- 

15 

45 

Horse  chestnut     .... 

35- 

9-5 

1 

Leaves  of  same,  10th  May 

72- 

50- 

1      Onlj 

•  those  salts  which  are  soluble  in     1 

From  23d  May  to  23d  July. 

84- 

24- 

f 

water  were  determined. 

From  27th  September  .    . 

86. 

13-5 

J 

Name  of  plant. 

Is 

1- 
■c-g 

100  Parjs  Ashes  contain 

is 

il 

2  2 

^ 

rbonates  of 
Earths. 

s 

< 

<*- 

i^ 

" 

IS 

Chestnut  blossoms   .    .    .71- 

50- 

Sunflower,  before  blossom- 

ing, 25th  June    .    .    .  141- 

79  67 

6-7 

013 

11-56 

1-5 

68- 

Ditto,  23d  July     ....  137- 

79-78 

6- 

0-12 

12- 

1-5 

61- 

Ditto,  with  seed  .... 

69-25 

22-5 

0-5 

4- 

375 

52- 

Pine  leaves  from  the  Jura, 

20th  June 

29- 

4013 

li27 

1-6 

43-5 

2-4 

16- 

Ditto,  from  siliceous  land  . 

39- 

34-5 

12- 

55 

29- 

19- 

15- 

Bilberries  (chalk  soil),  20th 

August 

26- 

36-38 

18- 

18- 

42- 

0-5 

17 

Bilberries  (siliceous  soils) 

••"■ 

41-5 

22- 

22- 

22- 

5- 

24 

APPENDIX. 


249 


1 

< 

Schmidt.                       l 
Bichon. 

Thon. 

Boussinganlt. 

Will  and  Fresenius. 

Bichon. 

Schmidt. 

Will  and  Fresenins. 

Bichon. 

Will  and  Fresenins. 

Boussingault. 

Levi. 

Letellier. 

Hruschauer. 

Roleck. 

Bichon. 

Souchay. 

Leuchtweiss. 

1^ 

bc-o      K  ^    a-       tea      ft      a                 a      e    a 

1    1      1      1    f    1    i    1    1    1    1    1    1        1    1    1    1    1    1    1    1 

•uinissBjoj 
JO  ©puoiqo 

1 1  1  1 1  i  1 1 1 lisi   1 1 1 1 1 1 1 1 

•tunipogjo 
optioiqo 

t-      CO          esasfo          osio 
II      1      11    II    1    Il6   iS       \tZ^  1    18^ 

•uoji 
JO  apixojaj 

«6    c     lort-^diort.^-^.^       loio^A^oM 

•BOiUS 

3-37 
0-42 

1-91 

1-31 

21-99 

2910 

0-17 

64-50 

533 

54-25 

0-8 
18-89 
29-30 
5903 

0-69 

14-04 
0-92 

•PPV 
oijnqding 

0-27 

101 

0-17 
0-26 

1-46 

0-51 

0-83 

1-0 

2-15 

0-59 
0-68 
0-35 
2-16 

010 
0-99 

•ppv 

ouoqdsoqj 

60-39 
46-14 

45-53 

48-30 
49-21 
49-32 
40-63 
38-48 
47-29 
51-81 

382 
14-9 

1-94 

50-1 

11-76 

18-76 

18-19 

50-07 

54-99 

34-96 

40-11 

•9UIIT 

•BIS8U38W 

•BpOg 

0-44 

27-79 

10-34 

15-75 
16-79 

4-45 

18-89 

1301 

-8 

39-92 
10-57 
1-31 
20-10 
1124 
0-66 
0-71 

•qsujoj 

25-90 
643 

2417 

30-12 
33-84 
21-87 
3-91 
20-91 
32-76 
11-43 
17-19 
12-3 
1218 

3f 
14-46 
4-00 
9-58 
8-74 
9-53 
21-67 
25-85 

•JU03 

iad  saqsy 

1    1     1     1    1    II    1    1    1    1    1    1       l^bd^l    1    ill 

Plants,  or  parts  of 
plants. 

*  Wheat,  grain  .    .    . 

*  Wheat,  grain  .    .    . 

*  Wheat,  grain  .    .    . 

Wheat,  grain .    .    . 

*  White  wheat  grain. 

*  Red  wheat  grain    . 

Barley,  grain  .    .    . 

*  Rye,  grain  .... 

*  Rye,  straw      .    .    . 
Oats,  grain     .    .     . 

*  Oats,  straw     .    .    . 

Maize,  grain  .    .    . 
Maize,  straw  .    . 

*  Mi'let,  grain    .    .    . 

*  Buckwheat,  gRxin  . 

*  Madia  sativa  .     .     . 

*  Henipseed  .... 
♦Linseed 

12* 


,390 


APPENDIX. 


1        1 


«  o  e  K  o 


1 


3B3    S    y    h5 


gigs 


bo 


•inntssiijoj 
JO  ©pijoiqo 


•lunipog 
JO  apjjomo 


•uoai 
JO  opixojaj 


•BOins 


•ppv 

ounqding 


•pioV 
ouoqdsoTij 


"ounq 


•BlSGUguj^ 


•■epog 


•Hsvjod 


•juao 
jad  saqsy 


0.3 


I  I  I  I  I  I  i  i  I  I  I  I  I     I  I  i  I  I  I  I  I     MM 


M  M  M  i:^M6M  ill      II  II  II  II 


I  I  i 


:s;?? 


1  r-cd»     I    -rfpOM 


tb  i.T  -^  -^  -^  .^  1^  ih  i:  ih 


ip  M  O  S  O  I-- 


(  10  m  o  >o  'S' 

'  tb  C5  C5  5«  i^ 


!!cio(MO^oi--.>n'^into 


»C  O  C5 


ss 


—  «  -sC  do  cb  c-»  do  do  i  t^ 


(j»  05  t^  do  -^  D. 


o!  -^  «  *»  =>  ^  r-  I  di  -^ 


■^  i  C! 


I-  pH  I   O  •>(>«  ^ 

•i  (N       I  «  o  do 


C5  QC  X  O  O  I- 


55  ®» 


Mrs  00 


II  II  II  II 


^  ,s;sj 


I  f2c<e»(No<9«      I   I   I 


1-2 


sigslt 


r  :=  .S  ~  J=  r 


-*  *      ♦  #  #  ♦  * 


S  ."Sf  1 
S    $|s 

«!  o  e  IT  s 


>#  #•< 


APPENDIX. 


23 


j 
Loc  ility  of  1 
tho  Plant.   !              Analyst. 

.i 

c 

lil  li 

1 

Denninger. 
Kleinschuiidt. 

Wrighton. 

L.  Hofmann. 
Poleck. 

1  ottinger. 

1 

fl  1  iff 

b         o5 

i 

sec;             a 
v      u      o             « 
SS      S      %             % 
»      «      «             « 

'6    '6    o         o 

d 
O 

•juni^srjoj 

J  >  apijomo 

•iimp:>H 
JO  apuoiqo 

1 1 1 1 1 l|| 

5« 

^1 1 1 1 1 1  iiii 

6^ 

giinese. 

18-17 

Red 

oxiae 
of  man- 
ganese. 

1315    . 

1  1  1  1  1  1  1              1  1  1  1  1  1  1  1              1 

iiiiiliS 

o 

•UOJ( 

JO  aptxojaj 

! 

•"!IIS 

2  O  CS  5-«  -^  -^  r^ 

1 

-p:ov 

ojanqding 

o  1  -<oo«b  1  Ai 

P 

•ppV 
atjoqd^oqj 

51  S  SI  t>J  r-  fN  00 

1 

•auiiT 

1 

•Kisau3aj^ 

LO  X  -*  S5  ;^  X  ;^ 

5! 

•..pog 

c;  «  '^»  i-      ■*  o 
■*  w  6*  -^  1  (i<  c> 

M    1  M  C=  -^  ih  -<  12 

g 

•i[srioj 

Ji3 

oliil  M 

1  1 1 1  1  1  i| 

1 

a 

•i^.g       ■       ■       ■       .       . 

Wood. 
Seeds. 

Bark. 

B.rk. 

Wood. 

r  Seeds. 

Wood. 

1 

.  ...->wr 

*******  5^ 

1 

o 

^5» 


APPENDIX. 


PolecJ 
Levi. 
Kiichl 

Kochl 

Maj-. 

i2 

1 

Giessen 
Giessen 

Alsace 
Zealand 

1 

Banat 

Fiinfkir- 
chen 

•imiJSSBJOJ 


•lunipog 
JO  apjjoiiio 


•noJi 
JO  apixojoj 


•«ains 


•PPV 
ounndiug 


PPV 
ouoqdsoqj 


•omiq 


-msaa3Ki\[ 


•Bpos 


•JISBJOJ 


•juao 
jad  saqsy 


»2  0h 


a    o    a 


i  M  M  i  I  I  I  i  i  I  I  I  I  I  I  I  I  I    I    I    III 


I    I  tb   I  ■*   1    I    I  -^  M  do  I  tc  M  3^  6<  -^   I  C5  A(    n    >o    ih  ii  c» 


•^  it  T^  6  di  d»  «5  •*  ■* -Jr  ■♦  6» « -^f  >o -Jf  o  d»  6 -^     I      I      I    I    I 


l^  l^  rt  'H  »  >-H     I       ,       .       I       .       I       I       I       I       I    !fl  1— I  O  Si      l^      M      t-  00  O 

•^  ih  o  -^  CO  M  I    I    I    I    I    I    I    I    1    I  ^  di  tb  C5   o    -^   ift  dj  ih 


I  di  (N  d<  -^  d«  «  M  «  o  rt> « ch  «  o  d«  ih  "h  rs  o    -^    di    «3  o  ■* 


>5  t^  s:  ifl  M  'T  -r  X  3V  CJ  3  iS  ' 

COO->1«-sS-H'*t-QOS>rt5lO: 


5«  5»  -^  '>»  rt  to  O     n     &    «  l-»  (X) 


i~  — 1  C5  -.o  ifs  ir:  51 1^  M  i-  S3  o  i?5  «fl  » t-  1^  «  -<  5> 
to  Ci  d«  d»  d»  d»  i^  do  I-  lo  CO  .^  -i<  ih  ih  d»  ih  d»  ■*  « 


O  lO  to  — < 
r-  to  QD  -v 
r-    PICS'* 


tbtcM  J 


I    I    i    l6  II    I    I 


1 1 


n  ^  s: 


1*1  {^00 

»--^so 


is 


RSS 


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I  I  I 


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a  e-g 


■••3  J  " 


ssrs 


1^ 


APPENDIX. 


2o3 


■3 

B 

< 

§ 

.£3 
S 

S 

m 

£ 

I 

fa. 

Trinidad 

Denierara 
Island  of 
Granada 

Jamaica 

Trelawney 

Jamaica 

St.  James 

Jamaica 

St.  James 

young  plants 

Hoffmans- 

gave 
Heligoland 

Cape 
Good  Hoi)e 
West  Indies 

III 

1    1    I    1    1    1        i 

1 

1 

III- 111 

0   s- 

1 

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JO  apijomo 

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apiiomo 

1 

I 

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joapipoi^ 

1 1    1 

1 

1 

1    i    1    1    1    1        1 

1 

I 

n  1 

00 
0 

I 

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JO  apixoaaj 

1  1  M  1  1     1 

1 

1 

iiiii 

1 1  1 

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^ 
% 

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1 

§ 

•ppv 
ounqding 

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0  i^  'i  I- 1-  0      n 

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i  1  1  1  1  1    1 

1 

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1 

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Sacchaniin             IV. 

V. 

VI. 

officinarum           VII. 

VIII. 

IX. 

X. 

^ 

M 

•a  >•  c  93  d 
##**■§ 

•snonj[  »J 

LRminaria  digitata     . 
EklonJa  buccinalis      . 

Padina  pavonia .    .    . 

3 

1 

> 

1- 

9 

S 

1 

254 


APPENDIX. 


i 

1 

I               1}       1 

Locality  of 
the  Plant. 

Greenland 

Hoffmans- 

gave. 

Bay  of 

Campoachy 

Atlantic 

Ocean 

Kattegat 

Kattegat 

Hoffmans- 

gave 

Kattegat 

Hoffmans- 

gave 
Kattegat 

•   G  lessen 
.   Giesseu 

1  1    1    1  nil  1  i  1  1 1  1 1  1 1 1  1 1  i  1 

•uintssTJioj 
JO  apuoiqo 

Mil       1     1    1    1    1    M  i  ii^PIII 

•tunipog 
joopuoiqo 

Hi  1    1   1  1 1  i  1  ipi  1 1 1 1  li 

•UOJI 

JO  apixojaj 

Ml  1  1 1 1 1  inmmM 

•T!3n!S 

•ppV 
ounqdiug 

II  IS  1  1 1  ii  immimi 

s  5  s  gi    ^  s  s  s  s  s,?c;j^?§8ss§?8 

•ppV 
OFJoqdsoqj 

oloo         00666    6^6.^«3t-t-^dD«M 

-auiiT 
•nisauSBW 

r-l       1         Al        6           T^        61     6       1      6l6t-00®OO-fM'^-«1<t^ 

•«pog 
•qsBjoa 

3,       gqS         ^gS?S?    §^S?,     1,11,1 
«     1      -^     6       ■*     moooc>;9;oj«illllll 

jad  saqsy 

S '5    S    S     g    S  S  S  S  i^  ,gSSi^g8j;g 

jl 

Fucus  vesiculosus     .    . 
Halidrys  siliquosa     .    . 

Sargassum  vulgare    .    . 

Sargassum  cocciferum  . 

Purcellaria  fastigiata    . 

Chondrus  crispus  .    .    . 
Chondrus  plicatus    .    . 
Iridffia  edulis    .... 
Polysiphonia  elongata  . 

Delesseria  sanguinea     . 

*  Datura  Stramon.  Seeds 
*Conium  maculat.   .    . 
♦Digitalis  purp.     .     .     . 

*  Chelidonium  m  .    .    . 

*  Agrostemma  Gith.  .    . 

*  Centaurea  Cyanus .    . 

*  Anthemis  arvensis 
*M-dtricaria    i             I. 

chamomilla  S            U. 

*  Acorus  Calamms     .    . 

APPENDIX. 


355 


ANALYSES  OF  ANIMAL  EXCREMENTS. 


1000  parts  of  human  feces  left  150  parts  of  ashes  (Berzelius),  which 
consist  of : — 


Phosphate  of  lime 
Phosphate  of  magnesia 
A  truce  of  gypsum 
Sulpliiitc  of  soda     • 
Sulphate  of  p<^ftash     . 
Pho-sphfitc  of  soda  . 
Carbonate  of  soda 
Sihca 
Charcoal  and  loss 


Cowdung. 

(Ha'dlen.) 
Phosphate  of  lime   ....    109 
Phosphate  of  magnesia  .    .        .        lO'O 
Peroxide  of  iron       .        .        .        .      8"5 

Lime 1"5 

Gypsum.  .        .        .        .        .        .3-1 

Chloride  of  potassium,  copper    .      traces. 

Silica t)3-7 

Loss 13 

1000 


100 


150 


Phosphate  of  lime 
Carbonate  of  lime 
Phosphate  of  magnesia 
Silica  .... 


Horsedung. 
(Jackson.) 
.      50 

18-75 
.    3625 

40 

10000 


According  to  Berzelius  there  are  contained  in — 


Urea 

Free  lactic  acid 

Lactate  of  ammonia    .... 

Extract  of  flesh 

Extractive  matter        .... 

Uric  acid 

Mucus  of  the  bladder  .... 

Sulphate  of  potash 

Sulphate  of  soda  .... 

Phosphate  of  soda  ..... 

Diphosphate  of  ammonia 1*65 

Common  salt 

Sal  ammoniac 

Phosphate  of  magnesia  and  lime  . 
Silica 


Water 


1000  parts 

100  parts 

Human 

5olid  residue 

Urine 

of  Urine. 

.    3010 

44-39 

•  1 17-14 

25-58 

■>vm 

1-49 

.      032 

0-48 

3-71 

554 

.       316 

4-72 

2-94 

439 

.       1-65 

2-46 

4-45 

0-64 

.      1-50 

223 

1-00 

1-49 

.      003 

005 

10000 

93300 

10(KM)0 


Z5r 


APPENDIX 


ANALYSES  OF  URINE  BY  LEG  ANN.* 


URINE. 

In  1000  Parts.                                      | 

B 

1 

•si 

II 

m 

1  iiS 

/ 

1 

5 

age 

"1  20  years  . 

93000 

30-00 

112 

4-60 

4-42 

0-39 

0-41 

Of  a  Man 
aged 

22  years  . 

928-80 

21-88 

0-97 

2-40 

545 

0-24 

1-64 

J>.38  years  . 

928-30 

27-80 

1-21 

3-70 

453 

0-47 

0-93 

86  years  . 

95300 

8-10 

0-43 

0-70 

292 

114 

0-29 

.  85  years  . 

959-50 

13-78 

024 

1-63 

2-92 

0-25 

0-27 

Ofa 

1 

Woman 

^28  years  . 

953-00 

1310 

0-24 

017 

225 

1-15 

0-46 

aged 

J 

Of  a  Girl 

aged 
Ofa  Boy 

( 19  years  . 

>   8  years  . 
S   3  years  . 

941-00 

24-59 

0-63 

0-80 

7-85 

2-43 

0-62 

94800 

19-20 

0-23 

3-80 

321 

0-52 

0-85 

aged* 

96100 

17-30 

024 

ANALYSES  OF  URINE  BY  LEHMANN.f 


i 

2 

if 

S    . 

II 

1 

1 

h\ 

auality  of  Urine. 

3 

1 

12 

^ 

■a  <u  6 

o   S 

r/2 

c 

o 

M 

ja 

2  « 

<- 

t 

o  2  , 

Urine  in  cases  of  " 

934-002 

65-998 

32-914 

1-073 

13-J80 

3-602 

7-289 

3-666 

1-187' 

very  strictly  re- 
gulated     ordi- 

^937-682 

62-318 

31-450 

1021 

14-185 

3-646 

7314 

3-765 

1132 ; 

nary  diet .    .    .  , 

932-019 

67-981 

32  909 

1-098 

14-859 

3712 

7321 

3-989 

1-108: 

Urine  frona  ani- 

909-32 

96-68 

53-79 

1-41 

9-36 

5-37 

11-51 

552 

3-72    1 

mal  food  ... 

933-27 

66-73 

41-65 

1-18 

6-62 

346 

7-08 

404 

2-70  ; 

Urine  from  vege- 
table food    .    . 

929-10 

70-90 

a3-3i 

117 

25-70 

3-80 

7-16 

354 

1-22   ' 

^941-91 

.58-09 

2242 

1-01 

18-49 

307 

7-14 

3-()8 

1-09  ; 

934-92 

65-08 

25-69 

0-89 

82-62 

3-71 

7-23 

3-74 

1-11  1 

Urine  from  non-  " 
nitrogenized 
food     .    .    .    .. 

.953-98 

46-02 

18-92 

0-89 

_ 

2-74 

325 

301 

1 

1-00   1 

955-11 

34-89    1108 

0-54 

114 

2-98 

5-48 

0-91 

*  Simon,  medicinlsche  Chemie,  Part  ii.,  pp.  357  and  358. 

t  Beitrige  zur  physiologiscben  und  pathologist  hen  Chemie,  ^c,  von  F.  SinoD,  Vol.  I. 
p.  180. 


APPENDIX 


Vo7 


URINE  OF  HERBIVORA.     ANALYSES  OF  VON  BIBRA." 


In  1000  Parts. 

URINE. 

Extractive 
Matter 

Soluble  in 
Water. 

Extractive 
Matter 

Soluble  in 
Alcohol. 

tS 

i 

s 

1 

Of  the  Horse 

II  J 

Of  the  Pig   .jj; 
Of  the  Ox    .  j{- 
Of  the  Goat  jj; 
Of  the  Hare    I. 

21-^2 

25-50 

18-26 
3-87 
3-99 
14  21 
10-20 
454 
468 

9-58 

23-40    i     18-80 

12-44 

12-60 
123 

555 

12-00 
1-25 

0-88 

005 

006 
005 
0-07 
007 
0-06 
006 
005 

- 

885-09 

912-84 
981-96 
982i>7 
91201 
9-2311 
980-07 
983-99 

91286 

^  19-25 
1-42 
112 
22-48 
1643 
1-00 
056 

32-68 

40 
909 
8-48 

24  42 

25-77 
8-50 
8-70 

23-70 

00 
0-88 
0-80 
1-50 
2-22 
0-80 
0-40 

12-64 

8-38 
2-73 
2-97 
19-76 
49-21 
3-78 
0-76 

8-54 

« 

f^ 

W 

H 

tf 

1^ 

<: 

o 

p^ 

> 

o 

o 

n 

>-, 

-1-1 

!/: 

^ 

<1 

< 

w 

ffi 

<< 

H 

ir; 

L^ 

o 

o 

t> 

pq 

M 

\A 

K 

fc 

o 

w 

^ 

1                                'aui-Tl  M3K»  "I  punoj  ai9A\  uoji  jo  saoejx                                 1 

,        -ssoT 

If 

1    £    I 

1 

1 

-BDtHS 

ii' 

i  ^    1 

eg-     »       ' 

1 

1 

•lunipog 
JO  epuomo 

6-94 

5f* 
with  a 
little 
chloride 
of  potas- 
sium 

53-1 
0-30 

14-7 

with  a 

little 
chloride 
of  potas- 
sium 

9d 

little 
chloride 
of  potas- 
sium 
22-49 

-B;s»a3Ki/\[  JO 
aaijqdsoijj 

1       I 

1    1 

t 

1    1 

t- 

-auiiq  JO 
an.'qdsoiij 

1       1 

s  ■ 

S 

-Bpog  JO 
ajuqdsoqj 

-upog 
JO  ajBqding 

1       1 

1   1    ' 

s 

1       1 

?   1  I 

a 

1 

•qsuioj 
JO  8j«iid(ns 

1  1   1 

1 

1 

•UpOg  JO 

ajwuoqjeo 

i 

':, 

1    1  1 

n 

1 

-qsTj^od  JO 
ojBuoqjuo 

i 

^ 

sil 

1 

-Bisau3Bi\[  JO 
ajBUoqiBQ 

05      n 

1  1  i 

1 

1 

•ainiq  jo 
ajBuoqjBo 

S    8 

10-7 

Spur. 

1 

1 

IS 

O 

Of  the  Pig   . 
Of  the  Ox    . 
Of  the  Goat 

1 

i 

♦  Annalen  der  Chemie  und  Pharmicie,  Vol.  liii.,  p.^. 


r  Ibid. 


258 


APPENDIX. 


URINE  OF  HERBIVORA 

ANALYSED   BY   BOUSSINOACLT.* 

Pig. 
Urea 490 

Hippurate  of  potash t 

Lactate  of  potash not  determined 

Carbonate  of  magnesia 087 

of  lime Spur 

SulphMte  of  potash 198 

Phosphate  of  potash 102 

Chloride  of  sodium 128 

Silica 0-07 

Water  and  organic  matter  not  determined  .       .  979-14 


100000 


Horse. 

Cow. 

3100 

18-48 

4-74 

1651 

d      2009 

1716 

41G 

4-74 

10-82 

0-55 

118 

360 

t 

t 

0-74 

152 

1-01 

Spur 

91076 

92132 

1000-00 


GUANO,  AFRICAN. 

ANALYSED    BY   TESCHEMACHER. 

Volatile  ammonia  and  salts,  as  oxalate,  phosphate,  and  humate,  with  animal  matters 

containing  5  per  cent,  ammonia 25 

Fixed  alkaline  salts,  as  chloride,  sulphate  and  phosphate  of  potassium    ...  11 

Phosphate  of  lime  and  magncsid. 32 

Water 30 

Earthy  matters               S 

100 


GUANO,  CHILIAN. 

ANALYSED    BY    COLQUHOUN. 

Urate  of  ammonia,  ammoniacal  salts,  and  decomposed  animal  matter         .                .  17-4 

Phosphate  of  lime  and  magnesia,  oxalate  of  lime 48-1 

Fixed  alkaline  salts 10-8 

Stony  mutters .  1'4 

Moisture 22*3 

100 
{Lond.,  Edinb.,  and  Dvhl.  Phil.  Mag.,  1S44,  May  and  June) 


CHILIAN  GUANO. 

ANALYSED    BY   DR.   URE. 

Combustible,  organic,  and  volatile  matter,  containing  2i  per  cent,  of  ammonia  .  J&5 

Water 24 

Silica 0-5 

Phosphate  of  lime 53 

100 


*  Annales  de  Chimie  et  der  Phys.,  Septembre,  1845,  p.  97. 

t  Hippuric  acid  could  not  be  detected  even  when  the  pig  with  its  food  (potatoes) 
\ejffi  rations  of  fresh  clover. 
X  No  phosphate  could  be  found. 


APPENDIX. 


359 


PERUVIAN  GUANO. 

ANALYSED   BY   DR.  IJRE. 

Nitrogenised  organic  matter,  including  urate  of  ammonia    .        .  50 

Water 11 

Phosphate  of  lime 25 

Phosphate  of  ammonia  and  magnesia,  phosphate  of  ammonia, 

oxalate  of  ditto,  containing  49  per  cent,  of  ammonia        .  13 

Silica  .....                1 

100 
{Lond.,  Edinb.,  and  Dubl.  Phil.  Mag.,  1844,  May  and  June.) 


AFRICAN  GUANO. 

ANALYSED  BY  DR.  URE. 

Saline  and  organic  matter,  containing  10  per  cent,  of  ammonia      .        .        .50 

Water 21-5 

Phosphate  of  lime  and  magnesia,  also  of  potash 26 

Silica 1 

Sulphate  of  potash  and  chloride  of  potassium 1-5 

100 

{Land.,  Edinb.,  and  Dubl.  Phil.  Mag.,  1S44,  May  and  June.) 


AFRICAN  GUANO. 

ANALYSED  BY  DR.  URK. 

Combustible  animal  matter 37 

Ammonia,  chiefly  as  phosphate 9*5 

Alkaline  and  earthy  phosphates 185 

Alkaline,  chiefly  potash  salts 6-0 

Silica  0*5 

Water  285 


100 


GUANO. 

ANALYSED    BY    KERSTEN.' 


Peru. 

Combustible  matter,  of  which  in  No.  I.  3  2,  in  II.  32. 
and  in  III.  6.5  per  cent,  of  humlc  acid,  and  of  uric 

acid  in  I.  27  per  cent,  in  the  others,  traces      .        .  36*5 

Ammonia 8-6 

Phosphate  of  lime  and  magnesia 205 

Phosphate,  sulphate,  and  chloride  of  potassium  and 

sodium 6-5 

Uuarzy  sand        .        .                1*5 

Water       .                .                , 280 

100 


II. 

Peru 

HI. 

Africn. 
Island  of 
Ichaboc. 

350 
7-5 

22-5 

395 
95 
175 

8-2 
2-0 
250 

7-3 

1-3 

250 

100 


•  Journal  of  Practical  Chemistry.  Vol.  xxxlv.,  p.  361. 


2  GO 


APPENDIX. 


OIUTjgjQ 

s    ?    §    ?    ? 
'^5    3    «=    <^    S 

•OBIU 

-omuiv  Itig 

-uinipog 
JO  apuomo 

29-22 

9-50 

286-31 

•uinissiBioj 
JO  opiJomo 

1       1       1       1      1 

-BpOg 

JO  ajBi^Jxo 

105-63 

-BIUOIUUIV 

}o  a»c[uxo 

74-0 
100-38 
93-9 
Spur. 

JO  aiBiidsoiij 

1      1      1       1       I 

-i?iu(>nuuv 
JO  ajRqdsoqj 

63-3 
30-06 
61-24 

•Bpog 
JO  ejBqdsoiij 

1     !     1     I    § 

CO      1 

•qsuioj 
JO  ajnqdsoiij 

20-02 
77-32 
14-94 
49-47 

-•fipog 
JO  sjBqding 

-qsnoj 
JO  ainqding 

i  $  ^  n  \z 
»^  "  i  -  s 

i    '    '    '    • 

•J3»BAV 

§    S    §    g    8 
1    ^    1    1    - 

^     «    a 

APPENDIX.  2G1 


GUANO. 

ANALYSED   BY   DR.  J.   DAVY 


American  Africat 

Guano.  Gaancx 

Soluble  matters,  oxalate,  phosphate,  and  chloride  of  ammonium, 

and  animal  matters 41-2  40*2 

Incombustible  and  insoluble,  chiefly  phosphate  of  lime  and  of 

magnesia 29  28-2 

Incombustible,  soluble,  chloride,  carbonate  and  sulphate  of  pot- 
ash         2-8  6-4 

Combustible,  sparingly  soluble,  chiefly  urate  of  ammonia        .  19 

Expelled  by  drying ;  water  and  carbonate  of  ammonia  ...  8  25*3 

100  100 

Davy  found  no  Urea  and  no  Oxalic  Acid. 

GUANO,  AFRICAN. 

ANALYSED   BY  FRANCIS. 

Volatile  salts,  as  oxalate  and  carbonate  of  ammonia,  sal  ammoniac,  and  combusti- 
ble organic  matter,  containing  550  per  cent,  of  humic  acid,  uric  acid,  and 

extractive  matter,  and  970  per  cent,  of  ammonia 4259 

Water 2713 

Phosphate  of  lime  and  magnesia 22*39 

Sand •        .        .        .  0-81 

Alkaline  salts,  chiefly  phosphate,  chloride,  and  a  little  sulphate  of  potassium  .        .  7-08 

100 
{Land.,  Edin.,  and  Duhl.  Phil.  Mag.,  1844,  May  and  June.) 

ANALYSIS  OF  A  BROWNISH  YELLOW  GUANO. 

BY   OELLACHKR.* 

Sal  ammoniac 2*25 

Urate  of  ammonia   . 12-20 

Oxalate      ditto 17-73 

Phosphate  ditto 690 

Carbonate  ditto 0-80 

Humate      ditto 1-06 

Phosphate  of  ammonia  and  tnagnesia       ....  11-63 

Phosphate  of  lime 20-16 

Oxalate  of       ditto 1-30 

Carbonate  of  ditto 1-65 

Chloride  of  sodium 0-40 

Sulphate  of  potash 4*00 

of  soda 4-92 

Waxy  matter 0-75 

Sand 1-68 

Water 4-31 

Undetermined  organic  matter    ...                ...  826 

100-00 
Centralblatt.,  1844,  p.  17    — Buchner,  Reperlorium,  vol.  ixxii.,  pp.  289— l2Qk 


262 


APPENDIX. 


2.— CONSTITUENTS  SOLUBLE  IN  HOT  WATER,  IN  1000  PARTS. 


Phosphate 
of  Lime. 

Phosphate 
of  Soda. 

Phosphate 

of  Am- 
monia and 
Magnesia. 

Uric  Acid. 

Urate  of 

Organic 
Matter 

I. 

ir. 
in. 

1         1-86 
2-88 

11-37 
110 

1-20  (?) 
1-28  (?) 
Spur. 
Spur. 

5-64 
4-04 
7-84 
Spur. 
133 

2516 

154-18 
2512 

11-80 
6-38 
8-60 

10-00 
7-56 

3.— CONSTITUENTS  INSOLUBLE  IN  WATER,  IN  1000  PARTS. 


"c 

o    . 

^ 

<« 

2  ^ 
■5.3 

CLfcc 

B 

o 

.a 

1 

Peroxide 
Iron  and 
Alumina 

i 

11 

i 
1 

1' 

I  i    197.50 
^•\    19200 

20-30 

25-60 

1560 

26-36 

34-50 

0-44 

19-84 

107-26 

16-48 

— 

20-60 

11-40 

42-42 

i-50 

„  {      62-70 
I^-      664-47 

8-74 

109-58 

7-20 

— 

8-62 

— 

49-74 

4-98 

30-56 

— 

20-43 



29-73 

— 

80-60 

268 

III.      13113 

25-80 

4-20 

1-50 

18-36 

— 

— 

ANALYSES  OF  ANIMAL  EXCREMENTS. 


Guano. 

A  sample 

from  Liverpool 

Bartels. 

Sal  ammoniac 6-500 

Oxalate  of  ammonia 13-351 

Urate  of  ammonia       ...  .        .    3244 

Phosphate  of  ammonia 6250 

Wnxy  matter 0600 

Sulphate  of  potash 4227 

Sulphate  of  soda 1119 

Phosphate  of  soda 5291 

Phosphate  of  ammonia  and  magnesia      .        .    4-196 

Common  salt 0100 

Phosphate  of  lime 9  940 

Oxalate  of  lime 16360 

Alumina       ..'...  .0104 

Residue  insoluble  in  nitric  acid    .        ..        .         5-800 
Loss  (water,  ammonia,  undetermined  organic 

matter)  ....  ...  22-718 

100000 


Guano.  ] 
from  Lima 

Nightingales' 
dung. 

Volkel. 

Braconnot. 

4-2 
100 
90 
60 

0-2 

52-7  with  iwtash 
0-8  with  potash 

55 
38 

3-3 

2-6 

143 
70 

0-2 
0-8 

4a 

4-7 

323 

37-7 

APPENDIX.  263 


ANALYSES  OF  THE  ASHES  OF  THE  SOLID  EXCREMENTS  OF 
THE  HORSE. 

BY  JOHN    ROBINSON    ROGERS. 


The  fresh  excrements  consist  of— 

Organic  matter 19-68 

Inorganic  matter  or  ashes 3-07 

Water       .        .  7725 

10000 


In  100  parts  of  the  ashes  there  are  contained  of  matter- 
Soluble  in  water 3-16 

Soluble  in  hydrochloric  acid 22-59 

Insoluble  in  both 74-45 

100-00 


COMPOSITION  IN  100  PARTS. 


Of  the  Matter 
soluble  in  Water 
^nd  in  Acid. 
Silica    .        .  ....      6-13 

Potash  ....        24-55 

Soda 0-00 

Oxide  of  iron 442 

Lime 14-91 

Magnesia.        .        ,  .        .         10-70 

Oxide  of  manganese  .        .       .       0-00 

Phosphoric  acid  .        .         37-54 

Sulphuric  acid     .  ,  .      1-99 

Chlorine  .  ...  o-14 


Of  the  Residue, 

insc  uble  in  Water 

Of  the  whole 

and  Acid. 

Ash  together 

81-92 

62-40 

6-71 

11-30 

2-67 

1-98 

005 

117 

1-06 

4-63 

1-46 

384 

2«7 

2-13 

111 

10-49 

1-78 

189 

0-00 

0-U3 

037 

014 

100-00  lOOOO 


264 


APPENDIX. 


MARLE. 

ANALYSES   BY    DR.   K.   O.    F.   KROCKER  * 

The  locality  of  the  differen  t  kinds  is  on  the  left  bank  of  the  Rhine,  between 
Mayence  and  Worms. 


'• 

II. 

HI. 

IV. 

V. 

VI. 

vn. 

Carbonate  of  lime.  . 
Carbonate  of  mag-  t 

nesia    ....    J 

Potash 

Water 

•  Clay,  sand,  &  oxide  ) 

of  iron.  ...  J 
Ammonia      .... 

12-275 

0-975 

0-087 
2-036 

84-525 

0-0047 

14-111 

Spuren. 

0082 
2-146 

82-830 

0-0077 

18-808 

1-228 

0092 
2-111 

76-827 

0-0988 

20-246 

3211 

0091 
1311 

74-325 

0-0768 

2.5-176 

2-223 

0105 
1-934 

69-570 

0-736 

32143 

1-544 

0101 
1-520 

64-214 

00955 

36066 

1-106 

0163 
1555 

60-065 

00579 

TABLE  OF  THE  AMMONIA  CONTAINED  IN  THE  SOIL 

BY    DR.   KROCKEK.T 


Ammonia 
in  100  parts 

of  Earth 

dried  in  the 

Air. 

Ammonia  in  a 
stratum  of  solid 

Soils  examined. 

Specific 
Gravity. 

Matter  0  25 

metre  thick,  on 

1  hectare,  in 

pounds. 

Clay  soil,  before  manuring 

0-170 

2-39 

30314 

Clay  soil 

0-163 

2-42 

19733 

Surface  soil,  at  Hohenheim     . 

0-156 

2-40 

^^-^ 

Subsoil  of  the  same  field      . 

0104 

2-41 

12532 

Clay  soil,  before  manuring 

0-149 

2-41 

17953 

Clay  soil,  before  manuring  . 

0147 

2-<l 

17713 

Clay  ready  to  be  sowed  with  barloy 

0-143 

2-44 

17446 

Clay  soil,  before  manuring  . 

0139 

2-<l 

16749 

Loamy  soil,  before  manuring  . 

0-135 

2-45 

16537 

LoHniy  soil,  before  manuring 

0-1 M 

2-45 

16292 

Earth  from  America,  never  manured      . 

P-llO 

2-18 

12614 

Sandy  soil,  never  cultivated 

0-096 

2-50 

12000 

Loamy  earth,  dug  out       .... 

0088 

25 

11000 

Sandy  soil,  never  cultivated 

0056 

2-51 

7028 

Nearly  pure  sand 

0031 
0-0988 

2-61 

4045 
11952 

00955 

11552 

0-0768 

9288 

Marie               .        .\ 

0-0736      ^ 

2-42 

8904 

0-0579 

7004 

00077 

931 

0-0O17 

568 

*  Annalen  der  Chemie  und  Pharmacie  vol.  Ivii.,  p. 
t  Ibid.,  vol.  Iviii.,  1846. 


PART    II. 


THE  CHEMICAL  PROCESSES  OP  FERMENTATION,  DECAY. 
AND  PUTREFACTION. 


CHAPTER  L 

( •  hom ira I  Tnt nsJbrmations, 


WooDV  fibre,  sugar,  gum,  and  all  such  organic  compounds, 
suffer  certain  changes  when  in  contact  witli  other  bodies — that 
is,  they  suffer  decomposition. 

There  are  two  distinct  modes  in  which  these  decompositions 
take  place  in  organic  chemistry. 

When  a  substance  composed  of  two  compound  bodies,  crystal- 
lized oxalic  acid  for  example,  is  brought  in  contact  with  concen- 
trated sulphuric  acid,  a  complet*^'  decomposition  is  effected  upon 
the  application  of  a  gentle  heat.  Now,  crystallized  oxalic  acid 
is  a  combination  of  water  with  the  anhydrous  acid  ;  but  concen- 
trated sulphuric  acid  possesses  a  much  greater  affinity  for  water 
than  oxalic  acid,  so  that  it  attracts  all  the  water  of  crystallization 
from  that  substance.  In  consequence  of  this  abstraction  of  the 
water,  anhydrous  oxalic  acid  is  set  free  ;  but,  as  this  acid  cannot 
exist  in  a  free  state,  a  division  of  its  constituents  necessarily 
ensues,  by  which  carbonic  acid  and  carbonic  oxide  are  produced, 
and  evolved  in  the  gaseous  form  in  equal  volumes.  In  this 
example,  the  decomposition  is  the  consequence  of  the  removal 
of  two  constituents  (the  elements  of  water),  which  unite  with 
the  sulphuric  acid,  and  its  cause  in  the  superior  affinity  of  the 
acting  body  (the  sulphuric  acid)  for  water.  In  consequence  of 
the  removal  of  the  component  parts  of  water,  the  remaining  ele- 
13 


206  CHEMICAL  TRANSFORMATIONS. 

ments  enter  into  a  new  form  ;  in  place  of  oxalic  acid,  we  have 
its  elements  in  the  form  of  carbonic  acid  and  carbonic  oxide. 

This  form  of  decomposition,  in  which  the  change  is  effected  by 
the  agency  of  a  body  which  unites  with  one  or  more  of  the  con- 
stituents of  a  compound,  is  quite  analogous  to  the  decomposition 
of  inorganic  substances.  When  we  bring  sulphuric  acid  and 
nitrate  of  potash  together,  nitric  acid  is  separated  in  consequence 
of  the  affinity  of  sulphuric  acid  for  potash;  in  consequence, 
therefore,  of  the  formation  of  a  new  compound  (sulphate  of 
potash). 

In  the  second  form  of  these  decompositions,  the  chemical 
affinity  of  the  acting  body  causes  the  component  parts  of  the 
decomposing  body  to  combine,  so  as  to  form  new  compounds,  of 
which  either  both,  or  only  one,  combine  with  the  acting  body. 
Let  us  take  dry  wood,  for  example,  and  moisten  it  with  sulphuric 
acid  ;  after  a  short  time  the  wood  is  carbonized,  while  the  sul- 
phuric acid  remains  unchanged,  with  the  exception  of  its  being 
united  with  more  water  than  it  possessed  before.  Now,  this 
water  did  not  exist  as  such  in  the  wood,  although  its  elements, 
oxygen  and  hydrogen,  were  present ;  but  by  the  chemical  attrac- 
tion of  sulphuric  acid  for  water,  they  were  in  a  certain  measure 
compelled  to  unite  in  this  form;  and,  in  consequence  of  this,  the 
"carbon  of  the  wood  was  separated  as  charcoal. 

Hydrocyanic  acid  and  water,  in  contact  with  hydrochloric 
acid,  are  mutually  decomposed.  The  nitrogen  of  the  hydrocy- 
anic acid,  and  the  hydrogen  of  a  certain  quantity  of  the  water, 
unite  together  and  form  ammonia  ;  whilst  the  carbon  and  hydro- 
gen of  the  hydrocyanic  acid  combine  with  the  oxygen  of  the 
Water  and  produce  formic  acid.  The  ammonia  combines  with 
the  muriatic  acid.  Here  the  contact  of  muriatic  acid  with  water 
and  hydrocyanic  acid  causes  a  disturbance  in  the  attraction  of 
the  elements  of  both  compounds,  in  consequence  of  which  they 
arrange  themselves  into  new  combinations,  one  of  which — am- 
monia— possesses  the  power  of  uniting  with  the  acting  body. 

Inorganic  chemistry  can  pr^isent  instances  analogous  to  this 
class  of  decomposition  also ;  but  there  are  forms  of  organic  che- 
ihical  decomposition  of  a  very  different  kind,  in  which  none  of 
Ihe  component  parts  of  the  decomposing  matter  enter  into  combi- 


EXAMPLES.  261 


nation  with  the  body  which  determines  the  decomposition.  In 
cases  of  this  kind  a  disturbance  is  produced  in  the  mutual  attrac- 
tion of  the  elements  of  a  compound,  and  they,  in  consequence, 
arrange  themselves  into  one  or  into  several  new  combinations, 
which  are  incapable  of  suffering  further  change  under  the  same 
conditions. 

When,  by  means  of  the  chemical  affinity  of  a  second  body,  by 
the  influence  of  heat,  or  through  any  other  causes,  the  composi- 
tion of  an  organic  compound  is  made  to  undergo  such  a  change, 
that  its  elements  form  two  or  more  new  compounds,  this  manner 
of  decomposition  is  called  a  chemical  transformation  or  meta- 
morphosis. It  is  an  essential  character  of  chemical  transforma- 
tions, that  none  of  the  elements  of  the  body  decomposed  are 
singly  set  at  liberty. 

The  changes  designated  by  the  terms  fermentation,  decay, 
and  putrefaction,  are  chemical  transformations  effected  by  an 
agency  which  has  hitherto  escaped  attention,  but  the  existence 
of  which  will  be  proved  in  the  following  pages 


966  CHEMICAL  TRANSFORMATIONS. 


CHAPTER  II. 

On  the  Causes  which  effect  Fermentation,  Decay,*  and  Putrefaction. 

Attention  has  been  only  recently  directed  to  the  fact,  that  a 
body  in  the  act  of  combination  or  decomposition  exercises  an  in- 
fluence upon  any  other  body  with  which  it  may  be  in  contact. 
Platinum,  for  example,  does  not  decompose  nitric  acid  ;  it  may 
be  boiled  with  this  acid  without  being  oxidized  by  it,  even  when 
in  a  state  of  such  fine  division  that  it  no  longer  reflects  light 
(black  powder  of  platinum).  But  an  alloy  of  silver  and  platinum 
dissolves  with  great  ease  in  nitric  acid  :  the  oxidation  which  the 
silver  suffers,  causes  the  platinum  to  undergo  the  same  change  ; 
or,  in  other  words,  the  latter  body,  from  its  contact  with  the 
oxidizing  silver,  acquires  the  property  of  decomposing  nitric 
acid. 

Copper  does  not  decompose  water,  even  when  boiled  in 
dilute  sulphuric  acid  ;  but  an  alloy  of  copper,  zinc,  and  nickel, 
dissolves  easily  in  this  acid  with  evolution  of  hydrogen  gas. 

Tin  decomposes  nitric  acid  with  great  facility,  but  water  with 
difficulty  ;  and  yet,  when  tin  is  dissolved  in  nitric  acid,  hydro- 
gen is  evolved  at  the  same  time,  from  a  decomposition  of  the 
water  contained  in  the  acid,  and  ammonia  is  formed  in  addition 
to  oxide  of  tin. 

In  the  examples  here  given,  the  only  combination  or  decompo- 
sition which  can  be  explained  by  chemical  affinity  s  the  last.  In 
the  other  cases,  electrical  action  ought  to  have  retarded  or  pre- 

*  An  essential  distinction  is  drawn  in  the  followhig  part  of  the  work, 
between  decay  and  putrefaction  ( Verwesung  und  Fdulniss),  and  they  are 
shown  to  depend  on  different  causes ;  but  as  the  word  decay  is  not  gene- 
rally applied  to  a  distinct  species  of  decomposition,  and  does  not  indicate 
its  true  nature,  I  shall  in  future,  at  the  suggestion  of  the  author,  employ 
the  term  eremacatms  (from  iipifta  by  degrees,  and  «av«is  burring). — ^Bld. 


THEIR  CAUSE.  2G9 


vented  the  oxidation  of  the  platinum  or  copper  while  they  were 
in  contact  with  silver  or  zinc,  but,  as  experience  shows,  the  in- 
fluence of  the  opposite  electrical  conditions  is  more  than  counter- 
balanced by  chemical  action. 

The  same  phenomena  are  seen  in  a  less  dubious  form  in  com- 
pounds, the  elements  of  which  are  held  together  by  a  feeble 
affinity.  It  is  well  known  that  there  are  chemical  compounds, 
of  so  unstable  a  nature,  that  changes  in  temperature  and  elec- 
trical condition,  or  even  simple  mechanical  friction,  or  contact 
with  bodies  apparently  totally  indifferent,  cause  such  a  disturb- 
ance in  the  attraction  of  their  constituents,  that  the  latter  enter 
into  new  forms,  without  any  of  them  combining  with  the  acting 
body.  These  compounds  appear  to  stand  but  just  within  the 
limits  of  chemical  combination,  and  agents  exercise  a  powerful  in- 
fluence on  them,  which  are  completely  devoid  of  action  on  com- 
pounds of  a  stronger  affinity.  Thus,  by  a  slight  increase  of  tem- 
perature, the  elements  of  hypoclj4orous  acid  separate  from  one 
another  with  evolution  of  heat  and  light  ;  chloride  of  nitrogen 
explodes  by  contact  with  many  bodies,  which  combine  neither 
with  chlorine  nor  nitrogen  at  common  temperatures ;  and  the 
contact  of  any  solid  substance  is  sufficient  to  cause  the  explosion 
of  iodide  of  nitrogen,  or  of  fulminating  silver. 

It  has  never  been  supposed  that  the  causes  of  the  decomposition 
of  these  bodies  should  be  ascribed  to  a  peculiar  power,  different 
from  that  which  regulates  chemical  affinity, — a  power  which 
mere  contact  with  the  down  of  a  feather  is  sufficient  to  set  in 
activity,  and  which,  once  in  action,  gives  rise  to  the  decom- 
position. The  substances  have  always  been  viewed  as  chemical 
compounds  of  a  very  unstable  nature,  in  which  the  component 
parts  are  in  a  state  of  such  tension,  that  the  least  disturbance 
overcomes  their  chemical  affinity.  They  exist  only  by  the  vis 
inertia,  and  any  shock  or  movement  is  sufficient  to  destroy  the 
attraction  of  their  component  parts,  and  consequently  their  ex- 
istence as  definite  compounds. 

Peroxide  of  hydrogen  belongs  to  this  class  of  bodies  ;  it  is 
decomposed  by  all  substances  capable  of  attracting  oxygen  from 
it,  and  even  by  contact  with  many  bodies,  such  as  platinum  or 
silver,  which  do  not  enter    nto  combination  with  any  of  its  con 


870  CHEMICAL  TRANSFORMATIONS. 

stituents.  In  this  respect,  its  decomposition  depends  evidently 
upon  the  same  causes. as  those  which  effect  that  of  iodide  of  ni- 
trogen, or  of  fulminating  silver.  Yet  it  is  singular  that  the  cause 
of  the  sudden  separation  of  the  component  parts  of  peroxide  of 
hydrogen  has  been  viewed  as  different  from  those  of  common 
decomposition,  and  has  been  ascribed  to  a  new  power  termed  the 
CATALYTIC  FORCE.  Now,  it  has  Hot  been  considered,  that  the 
presence  of  the  platinum  and  silver  serves  here  only  to  accele- 
rate the  decomposition  ;  for  without  the  contact  of  these  metals, 
the  peroxide  of  hydrogen  decomposes  spontaneously,  although 
very  slowly.  The  sudden  separation  of  the  constituents  of  per- 
oxide of  hydrogen  differs  from  the  decomposition  of  gaseous 
hypochloious  acid,  or  solid  iodide  of  nitrogen,  only  in  so  far  as 
the  decomposition  takes  place  in  a  liquid. 

A  remarkable  action  of  peroxide  of  hydrogen  has  attracted 
much  attention,  because  it  differs  from  ordinary  chemical  phe- 
nomena. This  is  the  reduction  which  certain  oxides  suffer  by 
contact  with  this  substance,  on  the  instant  at  which  the  oxygen 
separates  from  the  water.  The  oxides  thus  easily  reduced,  are 
those  of  which  the  whole,  or  part  at  least,  of  their  oxygen  is  re- 
tained merely  by  a  feeble  affinity,  such  as  the  oxides  of  silver 
and  of  gold,  and  peroxide  of  lead. 

Now,  other  oxides  very  stable  in  composition,  effect  the  decom- 
position of  peroxide  of  hydrogen,  without  experiencing  the  small- 
est change  ;  but  when  oxide  of  silver  is  employed  to  effect  the 
decomposition,  all  the  oxygen  of  the  silver  is  carried  away  with 
that  evolved  from  the  peroxide  of  hydrogen,  and  as  a  result  of 
the  decomposition,  water  and  metallic  silver  remain.  When 
peroxide  of  lead  is  used  for  the  same  purpose,  half  its  oxygen 
escapes  as  a  gas.  Peroxide  of  manganese  may  in  the  same  man- 
ner be  reduced  to  the  protoxide,  with  the  liberation  of  oxygen,  if 
there  be  present  an  acid  to  exercise  an  affinity  for  the  protoxide 
and  convert  it  into  a  soluble  salt.  If,  for  example,  we  add  to 
peroxide  of  hydrogen  sulphuric  acid,  and  then  peroxide  of 
manganese  in  the  state  of  fine  powder,  much  more  oxygen  is 
evolved  than  the  compound  of  oxygen  and  hydrogen  could  yield  ; 
and  on  examining  the  solution,  we  find  a  salt  of  the  protoxide  of 


TL  EIR  CAUSE.  271 


manganese,  so  that  half  of  the  oxygen  has  been  evolved  from  the 
peroxide  of  that  metal. 

A  similar  phenomenon  occurs,  when  carbonate  of  silver  is 
treated  with  several  organic  acids.  Pyruvic  acid,  for  example, 
combines  readily  with  pure  oxide  of  silver,  and  forms  a  salt  of 
sparing  solubility  in  water.  But  when  this  acid  is  brought  in 
contact  with  carbonate  of  silver,  the  oxygen' of  part  of  the  oxide 
escapes  with  the  carbonic  acid,  and  metallic  silver  remains  in 
the  state  of  a  black  powder.     (Berzelius.) 

Now  no  other  explanation  of  these  phenomena  can  be  given, 
than  that  a  body  hi  the  act  of  combination  or  decomposition  ena- 
bles another  body,  with  which  it  is  in  contact,  to  enter  into  the 
same  state.  It  is  evident  that  the  active  state  of  the  atoms  of 
one  body  has  an  influence  upon  the  atoms  of  a  body  in  con- 
tact with  it ;  and  if  these  atoms  are  capable  of  the  same  change 
as  the  former,  they  likewise  undergo  that  change  ;  and  combina- 
tions and  decompositions  are  the  consequence.  But  when  the 
atoms  of  the  second  body  are  not  of  themselves  capable  of  such 
an  action,  any  further  disposition  to  change  ceases  from  the 
moment  at  which  i^»e  atoms  of  the  first  body  assume  the  state  of 
rest,  that  is,  when  the  changes  or  transformations  of  this  body  are 
quite  completed. 

This  influence  exerted  by  one  compound  upon  the  other,  is 
exactly  similar  to  that  which  a  body  in  the  act  of  combustion 
exercises  upon  a  combustible  body  in  its  vicinity  ;  with  this  dif- 
ference only,  that  the  causes  which  determine  the  commencement 
and  duration  of  the  condition  of  change  are  different.  For  the 
cause,  in  the  case  of  the  combustible  body,  is  heat,  which  is 
generated  every  moment  anew  ;  whilst  in  the  phenomena  of 
decomposition  and  combination,  which  we  are  considering  at  pre, 
sent,  the  cause  is  a  body  in  the  state  of  chemical  action,  which 
exerts  the  decomposing  influence  only  so  long  as  this  action 
continues. 

Numerous  facts  show  that  motion  alone  exercises  a  consi- 
derable influence  on  chemical  forces.  Thus,  the  power  of 
cohesion  does  not  act  in  many  saline  solutions,  even  when 
ihey  are  fully  saturated  with  salts,  if  they  are  permitted  to 
cool  whilst  at  rest.     In  such  a  case,  the  salt  dissolved  in  a  liquid 


273  CHEMICAL  TKANSKOKMATlUNS. 

does  not  crystallize;  but  when  a  grain  of  sand  is  thrown  into 
the  solution,  or  when  it  receives  the  slightest  movenneiit,  the  whole 
liquid  becomes  suddenly  solid  with  the  evolution  of  heat.  The 
same  phenomenon  happens  with  water,  for  this  liquid  may  be 
cooled  much  under  32°  F.  (0°  C),  if  kept  completely  undisturbed, 
but  solidifies  in  a  moment  when  put  in  motion. 

The  atoms  of  a  body  must  in  fact  be  set  in  motion  before  they 
can  overcome  the  vis  ineriicE  so  as  to  arrange  themselves  into  cer- 
tain forms.  A  dilute  solution  of  a  salt  of  potash,  mixed  with  tar- 
taric acid,  yields  no  precipitate  whilst  at  rest ;  but  if  the  motion 
is  communicated  to  the  solution  by  agitating  it  briskly,  crystals 
of  cream  of  tartar  are  instantly  deposited.  A  solution  of  a  salt 
of  magnesia  also,  though  not  rendered  turbid  by  the  addition  of 
phosphate  of  ammonia,  deposits  the  phosphate  of  magnesia  and 
ammonia  on  those  parts  of  the  vessel  touched  with  the  rod  em- 
ployed in  stirring. 

In  the  processes  of  combination  and  decomposition  under 
consideration,  motion,  by  overcoming  the  vis  inertice,  gives  rise 
immediately  to  another  arrangement  of  the  atoms  of  a  body,  that 
is,  to  the  production  of  a  compound  which  did  not  before  exist  in 
it.  Of  course* these  atoms  must  previously  possess  the  power  of 
arranging  themselves  in  a  certain  order,  otherwise  both  friction 
and  motion  would  be  without  the  smallest  influence. 

The  simple  permanence  in  position  of  the  atoms  of  a  body, 
is  the  reason  that  so  many  compounds  appear  to  present  themselves, 
in  conditions,  and  with  properties,  different  from  those  which 
they  possess  when  they  obey  the  natural  attractions  of  their  atoms. 
Thus  sugar  and  glass,  when  m  Ited  and  cooled  rapidly,  are 
transparent,  of  a  conchoidal  fracture,  and  elastic  and  flexible  to 
a  certain  degree.  Put  the  ormer  becomes  dull  and  opaque  on 
keeping,  and  exhibits,  by  cleavage,  crystalline  faces  which  belong 
to  crystallized  sugar.  Glass  assumes  also  the  same  condition, 
when  kept  soft  by  heat  fur  a  long  period ;  it  becomes  white, 
opaque,  and  so  hard  as  to  strike  fire  with  steel.  Now,  in  both 
these  bodies,  the  atoms  evidently  have  diflerent  positions  in  the 
two  forms.  In  the  first  form  their  attraction  did  not  act  in  the  di- 
rection  in  which  their  power  of  cohesion  was  strongest.  It  is 
know^n  also,  that  when  sulphur  is  melted  and  cooled  rapidly  by 


THEIR  CAUSE.  273 


throwing  it  into  cold  water,  it  remains  transparent,  elastic,  and  so 
soil  that  it  may  be  drawn  out  into  long  threads ;  but  that,  after  a 
few  hours  or  days,  it  becomes  again  hard  and  crystalline. 

The  remarkable  fact  here  is,  that  the  amorphous  sugar  or  sul- 
phur  returns  again  into  the  crystalline  condition,  without  any 
assistance  from  an  exterior  cause ;  a  fact  which  shows  that  their 
molecules  have  assumed  another  position,  and  that  they  possess, 
therefore,  a  certain  degree  of  mobility,  even  in  the  condition  of 
a  solid.  A  very  rapid  transposition  or  transformation  of  this  kind 
is  seen  in  arragonite,  a  mineral  which  possesses  exactly  the  same 
composition  as  calcareous  spar,  but  of  which  the  hardness  and 
crystalline  form  prove  that  its  molecules  are  arranged  in  a  dif- 
ferent manner.  When  a  crystal  of  arragonite  is  heated,  an  inte-^ 
rior  motion  of  its  molecules  is  caused  by  the  expansion ;  the 
permanence  of  their  arrangement  is  destroyed  ;  and  the  crystal 
splinters  with  much  violence,  and  falls  into  a  heap  of  small 
crystals  of  calcareous  spar. 

It  is  impossible  for  us  to  be  deceived  regarding  the  causes  of 
these  changes.  They  are  owing  to  a  disturbance  of  the  state  of 
the  equilibrium,  in  consequence  of  which  the  particles  of  the 
body  put  in  motion  obey  either  other  affinities,  or  their  own 
natural  attractions. 

But  if  it  be  true,  as  we  have  just  shown  it  to  be,  that  mecha- 
nical motion  is  sufficient  to  cause  a  change  of  condition  in  many 
bodies,  it  cannot  be  doubted  that  a  body  in  the  act  of  composition 
or  decomposition  is  capable  of  imparting  the  same  condition  of 
motion  or  activity,  in  which  its  atoms  are,  to  those  of  certain 
other  bodies:  or,  in  other  words,  of  enabling  other  bodies  with 
which  it  is  in  contact  to  enter  into  combinations,  or  suffer  de- 
compositions. 

The  reality  of  this  influence  has  been  already  sufficiently 
proved  by  the  facts  derived  from  inorganic  chemistry  ;  but  it  is 
of  much  more  frequent  occurrence  in  the  relations  of  organic 
matter,  and  causes  very  striking  and  wonderful  phenomena. 

By  the  terms  fermentation,  putrefaction,  and  erebiacausis, 

are  meant  those  changes  in  form  and  properties  which  compound 

organic  substances,  undergo  when  separated  from  the  organism, 

and  expend  to  the  influence  of  water  and  a  certain  temperature. 

13* 


274  CHEMICAL  TRANSFORMATIONS. 

Fermentation  and  putrefaction  are  examples  of  the  kind  of  <ie- 
csomposition  which  we  have  named  transformations ;  the  elements 
of  the  bodies  capable  of  undergoing  these  changes  arrange  theov* 
selves  into  new  combinations,  in  which  the  constituents  of  water 
generally  take  a  part. 

Eremacausis  (or  decay)  differs  from  fermentation  and  putre- 
faction, inasmuch  as  it  cannot  take  place  without  the  access  of 
air,  the  oxygen  of  which  is  absorbed  by  the  decaying  bodies. 
Hence  it  is  a  process  of  slow  combustion,  in  which  heat  is  uni- 
formly evolved,  and  occasionally  even  light.  In  the  processes 
of  decomposition  termed  fermentation  and  putrefaction,  gaseous 
products  are  very  frequently  formed,  which  are  either  inodorous, 
or  possess  a  very  offensive  smell. 

The  transformation  of  those  matters  which  evolte  gaseous 
products  without  odor,  are  now,  by  pretty  general  consent,  desig- 
nated by  the  term  fermentation  ;  whilst  to  spontaneous  decom- 
position of  bodies  which  emit  gases  of  a  disagreeable  smell,  the 
term  putrefaction  is  applied.  But  the  smell  is,  of  course,  no 
distinctive  character  of  the  nature  of  the  decomposition,  for  both 
fermentation  and  putrefaction  are  processes  of  decomposition  of 
a  similar  kind,  the  one  of  substances  destitute  of  nitrogen,  the 
other  of  substances  containing  that  element. 

It  has  also  been  customary  to  distinguish  from  fermentation 
and  putrefaction  a  particular  class  of  transformations,  viz.  those 
whose  conversions  and  transpositions  are  effected  without  the 
evolution  of  gaseous  products.  But  the  conditions  under  which 
the  products  of  the  decomposition  present  themselves  are  purely 
accidental ;  there  is  therefore  no  i  eason  for  the  distinction  jusi 
mentioned. 


FERMENTATION  AND  PUTREFACTION.       17» 


CHAPTER  111. 

Fermentation  and  Putrefaction. 

Several  bodies  appear  to  enter  spontaneously  into  the  states 
of  fermentation  and  putrefaction,  particularly  such  as  contain 
nitrogen.  Now  it  is  very  remarkable  that  very  small  quantities 
of  these  substances,  in  a  state  of  fermentation  or  putrefaction, 
possess  the  power  of  causing  unlimited  quantities  of  similar  mat- 
ters to  pass  into  the  same  state.  Thus,  a  small  quantity  of  the 
juice  of  grapes  in  the  act  of  fermentation,  added  to  a  large 
quantity  of  the  same  fluid,  which  is  not  fermenting,  induces  the 
!>tate  of  fermentation  in  the  whole  mass.  So  likewise  the  most 
minute  portion  of  milk,  paste,  juice  of  the  beet-root,  flesh,  or 
blood,  in  the  state  of  putrefaction,  causes  fresh  milk,  paste,  juice 
of  the  beet-root,  flesh,  or  blood,  to  pass  into  the  same  condition 
when  in  contact  with  them. 

These  changes  evidently  differ  from  the  class  of  common  de- 
compositions effected  by  chemical  affinity  ;  they  are  chemical 
actions,  conversions,  or  decompositions,  excited  by  contact  with 
bodies  already  in  the  same  condition,  in  which  the  elements,  in 
consequence  of  the  disturbance,  arrange  themselves  anew,  ac- 
cording to  their  affinities.  In  order  to  form  a  clear  idea  of  these 
processes,  analogous  but  less  complicated  phenomena  must  pre- 
viously be  studied. 

The  compound  nature  of  the  molecules  of  an  organic  body, 
and  the  phenomena  presented  by  them  when  in  relation  with  other 
matters,  point  out  the  true  cause  of  these  transformations.  Evi- 
dence is  afforded  even  by  simple  bodies,  that  in  the  formation  of 
combinations,  the  force  with  which  the  combining  elements  ad- 
here to  one  another  is  inversely  proportional  to  the  number  of 
simple  atoms  in  the  compound  molecule.     Thus^prgiU^i^^.jjf 


270)  CHEiMICAL  TRANSFORMATIONS. 

lijangancse  by  absorption  of  oxygen  is  converted  into  the  sesqui- 
oxide,  the  peroxide,  manganic  and  hypermanganic  acids,  the 
number  of  atoms  of  oxygen  being  augmented  by  ^,  by  2,  by  3, 
and  by  3^.  But  all  the  oxygen  contained  in  these  compounds, 
beyond  that  whicii  belongs  to  the  protoxide,  is  bound  to  the  man- 
ganese by  a  much  more  feeble  affinity  ;  ii  red  lieat  causes  an 
evolution  of  oxygen  from  the  peroxide,  and  tljc  manganic  and 
hypermanganic  acids  cannot  be  separated  from  their  bases  with- 
out undergoing  immc-diate  decomposition. 

There  are  many  facts  wliich  prove,  lliat  the  most  simple  inor- 
ganic  compounds  are  also  the  inost  stable,  and  undergo  decom- 
position with  the  greatest  difficulty,  whilst  those  of  a  complex 
composition  yield  easily  to  changes  and  decompositions.  The 
cause  of  this  evidently  is,  that  in  proportion  to  the  number  of 
atoms  which  enter  into  a  compound,  the  directions  in  which  their 
attractions  act  will  be  more  numerous. 

Whatever  ide.'is  we  may  entertain  regarding  the  infinite  divisi- 
bility  of  matter  in  general,  the  existence  of  chemical  proportions 
removes  every  doubt  respecting  the  presence  of  certain  limited 
groups  or  masses  of  matter  which  we  have  not  the  power  of  divid- 
ing. The  particles  of  matter  called  equivalents  in  chemistry 
are  not  infinitely  small,  for  they  possess  a  weight,  and  are  capa- 
ble of  arranging  themselves  in  the  most  various  ways,  and  of  thus 
forming  innumerable  compound  atoms.  The  properties  of  these 
compound  atoms  differ  in  organic  nature,  not  only  according  to 
the  form,  but  also  in  many  instances  according  to  the  direction 
and  place,  which  the  simple  atoms  take  in  the  compound  mole- 
cules. 

When  we  compare  tlie  com{X)sition  of  organic  compounds  with 
inorganic,  we  are  quite  amazed  at  the  existence  of  combinations, 
in  one  single  molecule  of  which,  ninety  or  several  hundred  atoms 
or  equivalents  are  united.  Thus,  the  compound  atom  of  an  or- 
ganic acid  of  very  simple  composition,  acetic  acid  for  example, 
contains  twelve  equivalents  of  simple  elements  ;  one  atom  of  kinic 
acid  contains  thirty-three  ;  one  of  sugar  thirty-six  ;  one  of  amyg- 
dalin  ninety;  and  one  of  stearic  acid  138  equivalents.  The 
coniponent  parts  of  animal  bodies  are  infinitely  more  complex 
eveii  than  the^. 


OF  ORGANIC  COMPOUNDS.  277 


Inorganic  compounds  differ  ffom  organic  in  as  great  a  degree 
in  their  other  characters  as  in  their  simplicity  of  constitution. 
Thus,  the  decomposition  of  a  compound  atom,  as  of  sulphate  of 
potash,  is  aided  by  numerous  causes,  such  as  the  power  of  cohe- 
sion, or  the  capability  of  its  constituents  to  form  solid,  insoluble, 
or  at  certain  temperatures  volatile  compounds  with  the  body 
brought  into  contact  with  it,  and  nevertheless  a  vast  number  of 
other  substances  produce  in  it  not  the  slightest  change.  Now,  in 
the  decomposition  of  a  complex  organic  atom,  there  is  nothing 
similar  to  this. 

The  empirical  formula  of  sulphate  of  potash  is  SKO4.  It  con- 
tains only  1  eq.  of  sulphur,  and  1  eq.  of  potassium.  We  may 
suppose  the  oxygen  to  be  differently  distributed  in  the  compound, 
and  by  a  decomposition  we  may  remove  a  part  or  all  of  it,  or  re- 
place one  of  the  constituents  of  the  compound  by  another  sub- 
stance. But  we  cannot  produce  a  different  arrangement  of  the 
atoms,  because  they  are  already  disposed  in  the  simplest  form  in 
which  it  is  possible  for  tliem  to  combine.  Now,  let  us  compare 
the  composition  of  sugar  of  grapes  with  the  above:  here  12  eq. 
of  carbon,  12  eq.  of  hydrogen,  and  12  eq.  of  oxygen,  are  united 
together,  and  we  know  that  they  are  capable  of  combining  with 
each  other  in  the  most  various  ways.  From  the  formula  of  sugar, 
we  might  consider  it  either  as  a  hydrate  of  carbon,  wood,  starch, 
or  sugar  of  milk,  or  further,  as  a  compound  of  ether  with  alcohol, 
or  of  formic  acid  with  sachulmin.*  Indeed  we  may  calculate 
almost  all  the  known  organic  compounds  destitute  of  nitrogen 
from  sugar,  by  simply  adding  the  elements  of  water,  or  by  re- 
placing any  one  of  its  elementary  constituents  by  a  different  sub- 
stance. The  elements  necessary  to  form  these  compounds  are 
therefore  contained  in  the  sugar,  and  they  must  also  possess  the 
power  of  forming  numerous  combinations  amongst  themselves  by 
their  mutual  attractions. 

Now,  when  we  examine  what  changes  sugar  undergoes  when 
brought  into  contact  with  other  bodies  which  exercise  a  marked 
influence  upon  it,  we  find  that  these  changes  are  not  confined  to 

*  The  black  precipitate  obtained  by  the  action  of  hydrochloric  aci4  on 


2T!8  CHEMICAL  TRANSFORMATIONS. 

any  narrow  limits,  like  those  of  inorganic  bodies,  but  are  in  ftict 
unlimited. 

The  elements  of  sugar  yield  to  every  attraction,  and  to  each 
in  a  peculiar  manner.  In  inorganic  compounds,  an  acid  acts 
upon  a  particular  constituent  of  the  body  which  it  decomposes, 
by  virtue  of  its  affinity  for  that  constituent,  and  never  resigns  its 
proper  chemical  character,  in  whatever  form  it  may  be  applied- 
But  when  it  acts  upon  sugar,  and  induces  great  changes  in  that 
compound,  it  does  this  not  by  any  superior  affinity  for  a  base  ex- 
isting in  the  sugar,  but  by  disturbing  the  equilibrium  in  the  mu- 
tual attraction  of  the  elements  of  the  sugar  amongst  themselves. 
Muriatic  and  sulphuric  acids,  which  differ  so  much  from  one 
another,  both  in  characters  and  composition,  act  in  the  same 
manner  upon  sugar.  But  the  action  of  both  varies  according  to 
the  state  in  which  they  are  ;  thus,  they  act  in  one  way  when  di- 
lute, in  another  when  concentrated,  and  even  differences  in  their 
temperature  cause  a  change  in  their  action.  Thus,  sulphuric 
acid  of  a  moderate  degree  of  concentration  converts  sugar  into  a 
black  carbonaceous  matter,  forming  at  the  same  time  acetic  and 
formic  acid.  But  when  the  acid  is  more  diluted,  the  sugar  is 
converted  into  two  brown  substances,  both  of  them  containing 
carbon  and  the  elements  of  water.  Again,  when  sugar  is  sub- 
jected to  the  action  of  alkalies,  a  whole  scries  of  different  new 
products  are  obtained  ;  while  oxidizing  agents,  such  as  nitric  acid, 
produce  from  it  carbonic  acid,  acetic  acid,  formic  acid,  sac- 
charic acid,  and  many  other  products  which  have  not  yet  been 
examined. 

If,  from  the  facts  here  stated,  we  estimate  the  power  with  which 
the  elements  of  sugar  are  united  together,  and  judge  of  the  force 
of  their  attraction  by  the  resistance  which  they  ofierto  the  action 
of  bodies  brought  into  contact  with  them,  we  must  regard  the  atom 
of  sugar  as  belonging  to  that  class  of  compound  atoms,  which  exist 
only  by  the  vis  inerticR  of  their  elements.  Its  elements  seem 
merely  to  retain  passively  the  position  and  condition  in  which  they 
had  been  placed,  for  we  do  not  observe  that  they  resist  a  change 
of  this  condition  by  their  own  mutual  attraction,  as  is  the  case 
with  sulphate  of  potash. 

Now  it  is  only  such  compounds  as  sugar,  compounds  there 


OF  ORGANIC  COMPOUNDS.  279 

fore  possessing  a  very  complex  molecule,  which  are  capable 
of  undergoing  the  decompositions  named  fermentation  and  putre- 
faction. 

We  have  seen  that  certain  metals  acquire  a  power  which  they 
do  not  of  themselves  possess,  namely,  that  of  decomposing  watei 
and  nitric  acid,  by  simple  contact  with  other  metals  in  the  act  of 
chemical  combination.  We  have  also  seen,  that  peroxide  of 
hydrogen  and  the  persulphuret  of  the  same  element,  in  the  act  of 
decomposition,  cause  other  compounds  of  a  similar  kind,  but  of 
which  the  elements  are  much  more  strongly  combined,  to  undergo 
the  same  decom positron,  although  they  exert  no  chemical  affinity 
or  attraction  for  them  or  their  constituents.  The  cause  pro- 
ducing these  phenomena  will  be  also  recognised,  by  attentive  ob- 
servation, in  those  matters  which  excite  fermentation  or  putrefac- 
tion. All  bodies  in  the  act  of  combination  or  of  decomposition 
have  the  property  of  inducing  those  processes  ;  or,  in  other  words, 
of  causing  a  disturbance  of  the  statical  equilibrium  in  the  attrac- 
tions of  the  elements  of  complex  organic  molecules,  in  consequence 
of  which  those  elements  group  themselves  anew,  according  to 
their  special  affinities. 

The  proofs  of  the  existence  of  this  cause  of  action  can  be  easily 
produced  ;  they  are  found  in  the  characters  of  the  bodies  which 
effect  fermentation  and  putrefaction,  and  in  the  regularity  with 
which  the  distribution  of  the  elements  takes  place  in  the  subse- 
quent transformations.  This  regularity  depends  exclusively  on 
the  unequal  affinity  which  they  possess  for  each  other  in  an 
isolated  condition.  The  action  of  water  on  wood,  charcoal,  and 
cyanogen,  the  simplest  of  the  compounds  of  nitrog,<;n,  suffices  to 
illustrate  the  whole  of  the  transformations  of  organic  bodies;  of 
those  in  which  nitrogen  is  a  constituent,  and  of  tho$e  in  which  it 
is  absent. 


«80  CHEMICAL  TRANSFORMATIONS. 


CHAPTER   IV. 

On  the   Transformation  of  bodies  which   do   not  contain   Nitrogen  as  A 
constituent ;  and  of  those  in  which  it  is  present 

When  oxygen  and  hydrogen,  combined  in  equal  equivalents,  as 
in  steam,  are  conducted  over  charcoal,  heated  to  the  temperature 
at  which  it  possesses  the  power  to  enter  into  combin.ition  with  one 
of  these  elements,  a  decomposition  of  the  steam  ensues.  An 
oxide  of  carbon  (either  carbonic  oxide  or  carbonic  acid)  is  under 
tall  circumstances  formed,  while  the  hydrogen  of  the  water  is 
liberated.  This  proves  that  the  attraction  between  carbon  and 
oxygen  is  more  powerful,  at  a  high  temperature,  than  that  be- 
tween oxygen  and  hydrogen.  The  carbon  here  is  not  shared 
between  the  elements  of  the  water ;  for  no  carburetted  hydrogen 
is  formed. 

Acetic  and  meconic*  acids  suffer  a  true  transformation  under 
the  influence  of  heat,  that  is,  their  component  elements  are  dis- 
united, and  form  new  compounds  without  any  of  them  being 
singly  disengaged.  Acetic  acid  is  converted  into  acetone  and 
carbonic  acid  C 4  H,  Oj=C3  H,  O  +  CO2),  and  meconic  acid 
into  carbonic  acid  and  komenic  acid  ;  whilst,  by  the  influence 
of  a  higher  temperature,  the  latter  is  further  decomposed  into 
pyro-meconic  acid  and  carbonic  acid. 

Now,  in  these  cases,  the  carbon  of  the  bodies  decomposed  is 
shared  between  the  oxygen  and  hydrogen  ;  part  of  it  unites  with 
the  oxygen  and  forms  carbonic  acid,  whilst  the  other  portion  en- 
ters into  combination  with  the  hydrogen,  and  an  oxide  of  a  hydro- 
carbon is  formed,  in  which  all  the  hydrogen  is  contained. 

Tn  a  similar  manner,  when  alcohol  is  exposed  to  a  gentle  red 
heat,  its  carbon  is  shared  between  the  elements  of  the  water  ; 

*  An  add  existing  in  opiuni}  and  named  from  the  Greek  for  poppy. 


OF  BODIES  NOT  CONTAINING  NITROGEN.  28 1 


an  oxide  of  a  hydro-carbon  which  contains  all  the  oxygen 
(aldehyde),  and  some  gaseous  compounds  of  carbon  and  hydro- 
gen, being  produced. 

It  is  evident  that  during  the  transformation  caused  by  heat,  no 
foreign  affinities  can  be  in  play,  so  that  tlie  new  compounds  must 
result  merely  from  the  elements  arranging  themselves,  accord- 
ing to  the  degree  of  their  mutual  affinities,  into  new  combina- 
tions, which  are  constant  and  unchangeable  in  the  conditions 
under  which  they  were  originally  formed,  but  undergo  changes 
when  these  conditions  become  different.  If  we  compare  the  pro- 
ducts of  two  bodies,  similar  in  composition  but  different  in  pro- 
j>erties,  subjected  to  transformations  under  the  influence  of  two 
different  causes,  we  find  that  the  manner  in  which  the  atoms  are 
transposed  is  absolutely  the  same  m  both. 

In  the  transformation  of  wood  in  marshy  soils,  by  what 
we  call  putrefaction,  its  carbon  is  shared  between  the  oxygen 
and  hydrogen  of  its  own  substance,  and  of  the  water  :  car- 
buretted  hydrogen  is  consequently  evolved,  as  well  as  carbonic 
acid,  both  of  which  compounds  have  an  analogous  composition 
(CH„  COJ. 

Thus  also,  in  the  transformation  of  sugar  called  fermentation, 
its  elements  are  divided  into  two  porticMis  ;  the  one,  carbonic  acid, 
contains  -f  of  the  oxygen  of  sugar  ;  and  the  other,  alcohol,  con- 
tains all  its  hydrogen. 

In  the  transformation  of  acetic  acid,  produced  by  a  red  heat, 
carbonic  acid,  containing  f  of  the  oxygen  of  the  acetic  acid,  is 
formed,  and  acetone,  containing  all  its  hydrogen. 

It  is  evident,  from  these  facts,  that  the  elements  of  a  complex 
compound  are  left  to  their  special  attractions  whenever  their 
equilibrium  is  disturbed,  from  whatever  cause  this  disturbance 
may  proceed.  It  appears  also,  that  the  subsequent  distribution 
of  the  elements,  so  as  to  form  new  combinations,  always  takes 
place  in  the  same  way,  with  this  difference  only,  that  the  nature 
of  the  products  formed  is  dependent  upon  the  number  of  atoms 
of  the  elements  entering  into  action  ;  or,  in  other  words,  that 
the  products  differ  ad  infinitum^  according  to  the  composition  of 
the  origmal  substance. 


CHEMICAL  TRANSFORMATIONS. 


ON  THE  TRANSFORMATION  OF  BODIES  CONTAINING 
NITROGEN. 

By  the  examination  of  the  substances  most  prone  to  fermenta- 
tion and  putrefaction,  it  is  found  that  they  are  all,  without  excep- 
tion, bodies  containing  nitrogen.  In  many  of  these  compounds, 
a  transposition  of  their  elements  occurs  spontaneously  as  soon  as 
they  cease  to  form  part  of  a  living  organism  ;  that  is,  when  they 
are  drawn  out  of  the  sphere  of  attraction  in  which  alone  they  are 
able  to  exist. 

There  are,  indeed,  bodies  destitute  of  nitrogen  which  possess 
a  certain  degree  of  stability  only  when  in  combination,  but  which 
are  unknown  in  an  isolated  condition,  because  their  elements, 
freed  from  the  power  by  which  they  were  held  together,  arrange 
themselves  according  to  their  own  natural  attractions.  Hyper- 
manganic,  manganic,  and  hyposulphurous  acids,  belong  to  this 
class  of  substances,  which  however  are  rare. 

The  case  is  very  different  with  azotized  bodies.  It  woald 
appear  that  there  is,  in  the  nature  of  nitrogen,  some  peculiarity 
which  gives  its  compounds  the  power  to  decompose  spontaneously 
with  so  much  facility.  Now,  nitrogen  is  known  to  be  the  most 
indifferent  of  all  the  elements  :  it  evinces  no  particular  attraction 
to  any  one  of  the  simple  bodies  :  and  this  character  it  preserves 
in  all  its  compounds,  a  character  which  explains  the  cause  of  its 
easy  separation  from  the  matters  with  which  it  is  united. 

It  is  only  when  the  quantity  of  nitrogen  exceeds  a  certain 
limit,  that  azotized  compounds  have  some  degree  of  permanence, 
as  is  the  case  with  melamin,  ammelin,  &;c.  Their  liability  to 
change  is  also  diminished,  when  the  quantity  of  nitrogen  is  very 
small  in  proportion  to  that  of  the  other  elements  with  which  it  is 
united,  so  that  their  mutual  attractions  preponderate. 

This  easy  transposition  of  atoms  is  best  seen  in  the  fulminating 
silvers,  in  fulminating  mercury,  in  the  iodide  or  chloride  of  nitro- 
gen, and  in  all  fulminating  compounds. 

All  other  azotized  substances  acquire  the  same  power  of  de- 
composition, when  the  elements  of  water  are  brought  into  play  ; 
and  indeed  the  greater  part  of  thtm  are  not  capable  of  trans- 


OF  BODIES  COxNTTAlNlNG  NITROGEN.  283 

formation,  while  this  necessary  condition  to  the  transposition  of 
their  atoms  is  absent.  Even  the  compounds  of  nitrogen  most 
liable  to  change,  such  as  those  found  in  animal  bodies,  do  not 
enter  into  a  state  of  putrefaction  when  dry. 

The  result  of  the  known  transformations  of  azotized  substances 
proves,  that  water  does  not  merely  act  as  a  medium  in  which 
motion  is  permitted  to  the  elements  in  tlie  act  of  transposition, 
but  that  its  influence  depends  on  chemical  affinity.  When  the 
decomposition  of  such  substances  is  effected  with  the  assistance 
of  water,  their  nitrogen  is  invariably  liberated  in  the  form  of 
ammonia.  This  is  a  fixed  rule,  without  any  exceptions,  what- 
ever may  be  the  cause  which  produces  the  decompositions.  All 
organic  compounds  containing  nitrogen  evolve  the  whole  of  that 
element  in  the  form  of  ammonia,  when  acted  on  by  alkalies. 
Acids  and  increase  of  temperature  produce  the  same  effect.  It 
is  only  when  there  is  a  deficiency  of  water,  or  of  its  elements, 
that  cyanogen  or  other  azotized  compounds  are  produced. 

From  these  facts  it  may  be  concluded,  that  ammonia  is  the 
most  stable  compound  of  nitrogen  ;  and  that  hydrogen  and  nitro- 
gen possess  a  degree  of  affinity  for  each  other  surpassing  the 
attraction  of  the  latter  body  for  any  other  element. 

Already  in  considering  the  transformations  of  substances  des- 
titute of  nitrogen,  we  have  recognised  the  great  affinity  of  carbon 
for  oxygen  as  a  powerful  cause  for  effecting  the  disunion  of  the 
elements  of  a  complex  organic  atom  in  a  definite  manner.  But 
carbon  is  also  invariably  contained  in  azotized  organic  com- 
pounds, while  the  great  affinity  of  nitrogen  for  hydrogen  fur- 
nishes a  new  and  powerful  cause  of  change,  and  thus  facilitates 
the  transposition  of  their  component  parts.  Thus,  in  the  bodies 
destitute  of  nitrogen  we  have  one  element,  and  in  those  contain- 
ing that  substance,  two  elements  which  mutually  share  the  ele- 
ments of  water.  Hence  there  are  two  opposite  affinities  at  play, 
which  mutually  strengthen  each  other's  action. 

Now  we  know,  that  the  most  powerful  attractions  may  be  over- 
come by  the  influence  of  two  affinities.  Thus,  a  decomposition 
of  alumina  may  be  effected  with  the  greatest  facility,  when  the 
affinity  of  charcoal  for  oxygen,  and  of  chlorine  for  aluminium, 
are  both  put  in  action,  although   n*^ither  of  these  alone  has  any 


284  CHEMICAL  TRANSFORMATIONS. 

influence  upon  it.  There  is  in  the  nature  and  constitution  of  the 
compounds  of  nitrogen  a  kind  ol  tension  of  their  component 
parts,  and  a  strong  disposition  to  yield  to  transformations,  which 
effect  spontaneously  the  transposition  of  their  atoms  from  the 
instant  that  water  or  its  elements  are  brought  in  contact  with 
them. 

The  characters  of  the  hydrated  cyanic  acid,  one  of  the  sim- 
plest of  all  the  compounds  of  nitrogen,  are  perhaps  the  best 
adapted  to  convey  a  distinct  idea  of  the  manner  in  which  the 
atoms  are  disposed  of  in  transformations.  This  acid  contains 
carbon,  nitrogen,  hydrogen,  and  oxygen,  in  such  proj)ortions,  that 
the  addition  of  a  certain  quantity  of  the  elements  of  water  is  ex- 
actly  sufficient  to  cause  the  oxygen  contained  in  the  water  and 
acid  to  unite  with  the  carbon  and  form  carbonic  acid,  and  'the 
hydrogen  of  the  water  and  acid  to  combine  with  the  nitrogen  and 
form  ammonia.  The  most  favorable  conditions  for  a  complete 
transformation  are,  therefore,  associated  in  these  bodies,  and  it  is 
well  known  that  the  disunion  takes  place  on  the  instant  in  which 
the  cyanic  acid  and  water  are  brought  into  contact,  the  mixture 
being  converted  into  carbonic  acid  and  ammonia,  with  brisk  effer- 
vescence. 

This  decomposition  may  be  considered  as  the  type  of  the  trans- 
formations of  all  azotized  compounds  ;  it  is  putrefaction  in  its 
simplest  and  most  perfect  form,  because  the  new  products,  the 
carbonic  acid  and  ammonia,  are  incapable  of  further  transforma- 
tions. 

Putrefaction  assumes  a  totally  different  and  much  more  com- 
plicated form,  when  the  products  at  first  formed  undergo  a  further 
change.  In  these  cases  the  process  consists  of  several  stages,  of 
which  it  is  impossible  to  determine  when  one  ceases  and  the  other 
begins. 

The  transformations  of  cyanogen,  a  body  composed  of  carbon 
and  nitrogen,  and  the  simplest  of  all  the  compounds  of  nitrogen, 
will  convey  a  clear  idea  of  the  great  variety  of  products  which 
are  produced  in  such  a  case  :  it  is  the  only  example  of  the  pu- 
trefaction of  an  azotized  body  which  has  been  at  all  accurately 
studied. 

A  solution  of  cyanogen  in  water  becomes  turbid  after  a  short 


OF  BODIES  CONTAINING  NITROGEN.  285 

time,  and  deposits  a  black,  or  brownish  black  matter,  which  is  a 
combination  of  ammonia  with  another  body,  produced  by  the 
simple  union  of  cyanogen  with  water.  This  substance  is  inso- 
luble in  water,  and  is  thus  enabled  to  resist  further  change. 

A  second  transformation  is  effected  by  the  cyanogen  being 
shared  between  the  elements  of  the  water,  in  consequence  of 
which  CYANIC  ACID  is  formed  by  a  certain  quantity  of  the  cyano- 
gen combining  with  the  oxygen  of  the  water  ;  while  hydrocya- 
nic ACID  is  also  formed,  by  another  portion  of  the  cyanogen  unit- 
ing with  the  hydrogen  thus  liberated. 

Cyanogen  experiences  a  third  transformation,  by  which  a  com- 
plete disunion  of  its  elements  takes  place,  these  being  divided 
between  the  constituents  of  the  water.  Oxalic  acid  is  the  one 
product  of  this  disunion,  and  ammonia  the  other. 

Cyanic  acid,  the  formation  of  which  has  been  mentioned  above, 
cannot  exist  in  contact  with  water,  being  decomposed  immedi- 
ately into  carbonic  acid  and  ammonia.  The  cyanic  acid,  how- 
ever, newly  formed  in  the  decomposition  of  cyanogen,  escapes 
this  decomposition  by  entering  into  combination  with  the  free  am- 
monia, by  which  means  urea  is  produced. 

The  hydrocyanic  acid  is  also  decomposed  into  a  brown  matter 
containing  hydrogen  and  cyanogen,  the  latter  in  greater  propor- 
tion than  in  the  gaseous  hydrocyanic  acid.  Oxalic  acid,  urea, 
and  carbonic  acid,  are  also  formed  by  its  decomposition,  and 
formic  acid  and  ammonia  are  produced  by  the  decomposition  of 
its  radical. 

Thus,  a  substance  consisting  of  only  two  elements  (carbon  and 
nitrogen)  yields,  in  contact  with  water,  eight  totally  different  pro- 
ducts. Several  of  these  products  are  formed  by  the  transforma- 
tion of  the  original  body,  its  elements  being  shared  between  the 
constituents  of  water ;  others  are  produced  in  consequence  of  a 
further  change  in  those  first  formed.  The  urea  and  carbonate 
of  ammonia  are  generated  by  the  combination  of  two  of  the 
products,  and  in  their  formation  the  whole  elements  have  as- 
sisted. 

These  examples  show  that  the  results  of  decomposition  by  fer- 
mentation and  putrefaction  comprehend  very  different  pheno- 
mena.    The  first  kind   of  transformation   is  the  transposition  of 


HH  CHEMICAL  TRANSFORMATIONS. 

the  elements  of  one  complex  compound,  by  which  new  com- 
pounds are  produced  with  or  without  the  assistance  of  the  ele- 
ments of  water.  In  the  products  newly  formed  in  this  manner, 
either  the  same  proportions  of  those  component  parts  which 
Were  contained  in  the  matter  before  transformation  are  found, 
of  with  them  an  excess,  consisting  of  the  constituents  of  watfer 
which  had  assisted  in  promoting  the  disunion  of  the  elements. 

The  second  kind  of  transformations  consists  of  the  transposi- 
tions of  the  atoms  of  two  or  more  complex  compounds,  by  which 
the  elements  of  both  arrange  themselves  mutually  into  new  pro- 
ducts, with  or  without  the  co-operation  of  the  elements  of  water. 
In  this  kind  of  transformations,  the  new  products  contain  the  sum 
of  the  constituents  of  all  the  compounds  which  had  taken  a  part 
in  the  decomposition. 

The  first  kind  of  decomposition  characterizes  the  proper  fer- 
mentation  ;  the  other,  that  which  is  called  putrefaction.  We  shall, 
in  the  following  pages,  use  these  terms  invariably  for  these  two 
kinds  of  metamorphosis,  which  are  essentially  different  in  their 
results. 


FERMENTATION  OF  SUGAR.  387 


CHAPTER  V. 

Fermentation  of  Sugar. 

The  peculiar  decomposition  of  sugar  may  be  viewed  as  a  type 
of  all  the  transformations  designated  fermentation.* 

The  analysis  of  sugar  from  the  cane,  proves  that  it  contains 
the  elements  of  carbonic  acid  and  alcohol,  minus  1  atom  of  water. 
The  alcohol  and  carbonic  acid  produced  by  the  fermentation  of 
a  certain  quantity  of  sugar,  contain  together  one  equivalent  of 
oxygen  and  one  equivalent  of  hydrogen  ;  the  elements,  therefore, 
of  one  equivalent  of  water  more  than  the  sugar  contained.  The 
excess  of  weight  in  the  products  is  thus  explained  most  satisfac- 
torily ;  it  is  owing,  namely,  to  the  elements  of  water  having  taken 
part  in  the  metamorphosis  of  the  sugar. 

It  is  known  that  1  atom  of  sugar  contains  12  equivalents  of 
carbon,  botli  from  the  proportions  in  which  it  unites  with  bases, 
and  from  the  composition  of  saccharic  acid,  the  product  of  its 
oxidation.     Now  none  of  these  atoms  of  carbon  are  contained  in 

*  When  yeast  is  made  into  a  thin  paste  with  water,  and  1  cubic  centi- 
mitre  of  this  mixture  introduced  into  a  graduated  glass  receiver  filled  with 
mercury,  in  which  are  already  10  grammes  of  a  solution  of  cane-sugar, 
containing  1  gramme  of  pure  solid  sugar ;  it  is  found,  after  the  mixture 
has  been  exposed  for  24  hours  to  a  temperature  of  from  20  to  25  C.  (68 — 
77  F.),  that  a  volume  of  carbonic  acid  has  been  formed,  which,  at  0°  C. 
(32^^  F.),  and  an  atmospheric  pressure  indicated  by  07G  metre  Bar :  would 
be  from  245  to  250  cubic  centimetres.  But  to  this  quantity  we  must  add 
11  cubic  centimetres  of  carbonic  acid,  with  which  the  11  grammes  of  liquid 
would  be  saturated  ;  so  that  in  all,  256 — 261  cubic  centimetres  of  carbonic 
acid  are  obtained.  This  volume  of  carbonic  acid  corresponds  to  from 
0-503  to  0-5127  grammes  by  weight.  Thenard  also  obtained  from  1  gramme 
of  sugar  0-5262  grammes  of  absolute  alcohol.  100  parts  of  cane-sugar 
yield,  therefore,  of  alcohol  and  carbonic  acid  together  103*89  parts.  Now 
in  these  two  products  are  contained  42  parts  of  Carbon,  or  exactly  th* 
quantity  originally  present  in  the  sugar. 


i58  FERMENTATION  OF  SUGAR. 


the  sugar  as  carbonic  acid,  because  the  whole  quantity  is  obtaineo 
as  oxalic  acid,  when  sugar  is  treated  with  hypermanganate  of  pot- 
ash (Gregory)  ;  and  as  oxalic  acid  is  a  lower  degree  of  the  oxi- 
dation of  carbon  than  carbonic  acid,  it  is  impossible  to  conceive 
that  the  lower  degree  should  be  produced  from  the  higher,  by 
means  of  one  of  the  most  powerful  agents  of  oxidation  which  we 
possess. 

It  can  be  also  proved,  that  the  hydrogen  of  the  sugar  does  not 
exist  in  it  in  the  form  of  alcohol,  for  it  is  converted  into  water 
and  a  kind  of  carbonaceous  matter,  when  treated  with  acids, 
particularly  with  such  as  contain  no  oxygen  ;  and  this  manner 
of  decomposition  is  never  suffered  by  a  compound  of  alcohol. 

Sugar  contains,  therefore,  neither  alcohol  nor  carbonic  acid,  so 
that  these  bodies  must  be  produced  by  a  different  arrange- 
ment of  its  atoms,  and  by  their  union  with  the  elements  of 
water. 

In  this  metamorphosis  of  sugar,  the  elements  of  the  yeast,  by 
contact  with  which  its  fermentation  was  effected,  take  no  ap- 
preciable part  in  the  transposition  of  the  elements  of  the  sugar ; 
for  in  the  products  resulting  from  the  action,  we  find  no  compo- 
nent part  of  this  substance.  The  same  sugar  which  in  contact 
with  yeast  yields  alcohol  and  carbonic  acid  gives  rise,  when  in 
contact  with  putrefying  white  cheese,  to  butyric  acid,  hydrogen 
being  at  the  same  time  liberated.     (Pelouse  and  Gelis.) 

We  may  now  study  the  fermentation  of  a  vegetable  juice,  con- 
taining not  only  saccharine  matter,  but  also  such  substances  as 
albumen  and  gluten.  The  juices  of  parsneps,  beet-roots,  and 
onions,  are  well  adapted  for  this  purpose.  When  such  a  juice  is 
mixed  with  yeast  at  common  temperature,  it  ferments  like  a  solu- 
tion. Carbonic  acid  gas  escapes  from  it  with  effervescence,  and 
in  the  liquid,  alcohol  is  found  in  quantity  exactly  corresponding 
to  that  of  the  sugar  originally  contained  in  the  juice.  But  such 
a  juice  undergoes  spontaneous  decomposition  at  a  temperature  of 
from  95°  to  104°  (35° — 40°  C).  Gases  possessing  an  offensive 
smell  are  evolved  in  considerable  quantity,  and  when  the  liquor 
is  examined  after  the  decomposition  is  completed,  no  alcohol  can 
be  detected.  The  sugar  has  also  disappeared,  and  with  it  all  the 
azotized  compounds  which  existed  io  the  i^^9^  previously  to  ita 


YEAST  OR  FERMENT.  -889 


fermentation.  Both  ^vere  decomposed  at  the  same  time ;  the 
nitrogen  of  the?  azotized  compounds  remains  in  the  liquid  as  am- 
monia, and,  in  addition  to  it,  there  are  three  new  products,  formed 
from  the  component  parts  of  the  jui<je.  One  of  these  is  lactic 
acidr  the  slightly  volatile  compound  found  in  putrid  animal  mix- 
tures ;  the  other  is  the  crystalline  body  which  forms  tiie  principal 
cpBstituent  of  manna  ;  and  the  tiiird  is  a  mass  resembling  gum- 
af abic,  which  forms  a  thick  viscous  solution  with  water.  These 
three  products  weigh  more  than  the  sugar  contained  in  the  juice, 
even  without  calculating  the  weight  of  the  gaseous  products. 
Hence  tiiey  are  not  produced  from  the  elements  of  the  sugar 
alone.  None  of  these  three  substances  could  b6  detected  in  the 
juice  before  fermentation.  They  must,  therefore,  have  been 
ibrmed  by  the  interchange  of  the  elements  of  the  sugar  with 
those  of  the  foreign  substances  also  present.  It  is  this  mixed 
transformation  of  two  or  more  compounds  which  receives  the 
special  name  of  putrefaction. 


YEAST  OR  FERMENT. 

When  attention  i^  directed  to  the  condition  of  those  substances 
which  possess  the  power  of  inducing  fermentation  and  putre- 
faction in  other  bodies,  evidence  is  found  in  their  general 
characters,  and  in  the  manner  in  which  they  combine,  that 
they  all  are  bodies,  the  atoms  of  which  are  in  the  act  of  trans- 
position. 

The  characters  of  the  remarkable  matter  deposited  in  an  inso. 
iuble  state  during  the  fermentation  of  beer,  wine,  and  vegetable 
juices,  may  first  be  studied. 

This  substance,  called  yeast  or  ferment,  from  the  power 
which  it  possesses  of  causing  fermentation  in  sugar,  or  saccha- 
rine vegetable  juices,  possesses  all  the  characters  of  a  com- 
pound OF  NITROGEN  IN  THE  STATE  OF  PUTREFACTION  AND  ERBMA- 
CAUflS. 

14 


;tf90  YEAST  OR  FERMENT. 

Like  wood  in  the  state  of  eremacausis,  yeast  converts  the 
oxygen  of  the  surrounding  air  into  carbonic  acid,  but  it  also 
evolves  this  gas  from  its  own  mass,  like  bodies  in  the  state  of 
putrefaction.  (Colin.)  When  kept  under  water,  it  emits  car. 
bonic  acid,  accompanied  by  gases  of  an  offensive  smell  (Thenard), 
and  is  at  last  converted  into  a  substance  resembling  old  cheese 
(Proust).  But  when  its  own  putrefaction  is  completed,  it  has  no 
longer  the  power  of  inducing  fermentation  in  other  bodies.  The 
presence  of  water  is  quite  necessary  for  sustaining  the  proper- 
ties of  ferment,  for  by  simple  pressure  its  power  to  excite  fer- 
mentation is  much  diminished,  and  is  completely  destroyed  by 
drying.  Its  action  is  arrested  also  by  the  temperature  of  boiling 
water,  by  alcohol,  common  salt,  an  excess  of  sugar,  oxide  of 
mercury,  corrosive  sublimate,  pyroligneous  acid,  sulphurous 
acid,  nitrate  of  silver,  volatile  oils,  and  in  short,  substances,  all 
of  which  possess  antiseptic  properties. 

The  insoluble  part  of  the  substance  called  ferment  does 
NOT  cause  fermentation.  For  when  the  yeast  from  wine  or 
beer  is  carefully  washed  with  water,  care  being  taken  that  it  is 
always  covered  with  this  fluid,  the  residue  does  not  produce  fer- 
mentation. 

The  soluble  part  of  ferment  likewise  does  not  excite 
fermentation.  An  aqueous  infusion  of  yeast  may  be  mixed 
with  a  solution  of  sugar,  and  preserved  in  vessels  from  which  the 
air  is  excluded,  without  either  experiencing  the  slightest  change. 
What  then,  we  may  ask,  is  the  matter  in  ferment  which  excites 
fermentation,  if  neither  the  soluble  nor  insoluble  parts  possess  the 
power  ?  This  question  has  been  answered  by  Colin  in  the  most 
satisfactory  manner.  He  has  shown  that  in  reality  it  is  the 
^50LUBLE  part.  But  before  it  obtains  this  power,  the  decanted 
infusion  must  be  allowed  to  cool  in  contact  with  the  air,  and  to 
remain  some  time  exposed  to  its  action.  When  introduced  into 
a  solution  of  sugar  in  this  state,  it  produces  a  brisk  fermentation  ; 
but  without  previous  exposure  to  the  air,  it  manifests  no  such 
property. 

The  infusion  absorbs  oxygen  during  its  Exposure  to  the  ai/. 
and  cfirbonic  acid  may  be  found  in  it  after  a  short  time. 

Yeast    produces    fermentation    in    consequence   of  the   pro- 


ITS  PROPERTIES.  291 


gressive  decomposition  which  it  suffers  from  the  action  of  ail 
and  water. 

Now  when  yeast  is  made  to  act  on  sugar,  it  is  found  that 
after  the  completion  of  the  transformation  of  the  latter  substance 
into  carbonic  acid  and  alcohol,  part  of  the  yeast  itself  has  dis- 
appeared. 

From  20  parts  of  fresh  yeast  from  beer,  and  100  parts  of 
sugar,  Th6nard  obtained,  after  the  fermentation  was  completed, 
13*7  parts  of  an  insoluble  residue,  which  diminished  to  10  parts 
when  employed  in  the  same  way,  with  a  fresh  portion  of  sugar. 
These  ten  parts  were  white,  possessed  of  the  properties  of  woody 
fibre,  and  had  no  further  action  on  sugar. 

It  is  evident,  therefore,  that,  during  the  fermentation  of  sugar 
by  yeast,  both  of  these  substances  suffer  decomposition  at  the 
same  time,  and  disappear  in  consequence.  But  if  yeast  be  a 
body  which  excites  fermentation  by  being  itself  in  a  state  of 
decomposition,  all  other  matters  in  the  same  condition  should 
have  a  similar  action  upon  sugar ;  and  this  is  in  reality  the  case. 
Muscle,  urine,  isinglass,  osmazome,  albumen,  cheese,  gliadine, 
gluten,  legumin,  and  blood,  when  in  a  state  of  putrefaction,  all 
have  the  power  of  producing  the  putrefaction  or  fermentation  of 
a  solution  of  sugar.  Yeast,  which  by  continued  washing  has 
entirely  lost  the  property  of  inducing  fermentation,  regains  it 
when  its  putrefaction  has  recommenced,  in  consequence  of  its 
being  kept  in  a  warm  situation  for  some  time. 

Yeast  and  putrefying  animal  and  vegetable  matters  act  as 
peroxide  of  hydrogen  does  on  oxide  of  silver,  when  they  induce 
bodies  with  which  they  are  in  contact  to  enter  into  the  same 
state  of  decomposition.  The  disturbance  in  the  attraction  of  the 
constituents  of  the  peroxide  of  hydrogen  effects  a  disturbance 
in  the  attraction  of  the  elements  of  the  oxide  of  silver,  the  one 
being  decomposed  on  account  of  the  decomposition  of  the 
other. 

Peroxide  of  hydrogen  is  rapidly  decomposed  in  contact  with 
moist  fibrin  of  blood,  an  animal  substance  in  a  continuous  state 
of  decomposition.  The  oxygen  which  it  contained,  in  addition 
to  that  necessary  to  form  water,  escaped  with  violent  effer. 
vescence. 


399  YEAST  OR  FERMENT. 


.  Now  if  we  consider  the  process  of  the  fermentation  of  pure 
sugar,  in  a  practical  point  of  view,  we  meet  with  two  facts  of 
constant  occurrence.  When  the  quantity  of  ferment  is  too 
small  in  pmportion  to  that  of  the  sugar,  its  putrefaction  will  be 
completed  before  the  transformation  of  all  the  sugar  is  effected. 
Some  sugar  here  remains  undecomposed,  because  the  cause  of 
its  transformation  is  absent,  viz.  contact  with  a  body  in  a  state 
of  decomposition. 

But  when  the  quantity  of  ferment  predominates,  a  certain 
quantity  of  it  remains  after  all  the  sugar  has  fermented,  its 
decomposition  proceeding  very  slowly,  on  account  of  its  insolu- 
bility in  water.  This  residue  of  ferment  is  still  able  to  induce 
fermentation,  when  introduced  into  a  fresh  solution  of  sugar, 
and  retains  the  same  power  until  it  has  passed  through  all  the 
stages  of  its  own  transformation.  Hence  a  certain  quantity  of 
yeast  is  necessary  in  order  to  effect  the  transformation  of  a 
certain  portion  of  sugar,  not  because  it  acts  by  its  quantity  in 
increasing  any  affinity,  but  because  its  influence  depends  solely 
on  its  presence,  and  its  presence  is  necessary,  until  the  last  atom 
of  sugar  is  decomposed. 

These  facts  and  observations  point  out  the  existence  of  a  new 
cause,  which  effects  combinations  and  decompositions.  This 
cause  is  the  action  which  bodies  in  a  state  of  combination  or 
decomposition  exercise  upon  substances,  the  component  parts  of 
which  are  united  together  by  a  feeble  affinity.  This  action 
resembles  a  peculiar  power,  attached  to  a  body  in  the  state  of 
combination  or  decomposition,  but  exerting  its  influence  beyond 
the  sphere  of  its  own  attractions.  We  are  now  able  to  account 
satisfactorily  for  many  known  phenomena.  ■■■^. 

A  large  quantity  of  hippuric  acid  may  be  obtained  .  from  the 
fresh  urine  of  a  horse,  by  the  addition  of  muriatic  acid  ;  but 
when  the  urine  has  undergone  putrefaction,  no  trace  of  it  can 
be  discovered.  The  urine  of  man  contains  a  considerable 
quantity  of  urea  ;  but  when  the  urine  putrefies^  the  urea  entirely 
disappears.  When  urea  is  added  to  a  solution  of  sugar  in  the 
state  of  fermentation,  it  is  decomposed  into  carbonic- acid  and 
ammonia.  No  asparagin  can  be  detected  in  a  putrefied  infusion 
of  asparagus,  licorice-root,  or  the  root  of  marshmallow  (AWuHKl, 
officinalis). 


DIFFERENCE  OF  FERMENTATION  AND  PUTREFACTION.  293 

It  has  also  been  mentioned,  that  the  strong  affinity  of  nitrogen 
for  hydrogen,  and  that  of  carbon  for  oxygen,  are  the  cause  of  the 
facility  with  which  the  elements  of  azotized  compounds  are  dis* 
united  ;  those  affinities  aiding  each  other,  inasmuch  as  by  virtue 
of  them  different  elements  of  the  compounds  strive  to  take 
possession  of  the  different  elements  of  water.  Now  since  it  is 
found  that  no  body  destitute  of  nitrogen  possesses,  when  pure, 
the  property  of  decomposing  spontaneously  whilst  in  contact 
with  water,  we  must  ascribe  this  property  which  azotized  bodies 
possess  in  so  eminent  a  degree,  to  something  peculiar  in  the 
nature  of  the  compounds  of  nitrogen,  and  to  their  constituting,  iti 
a  certain  measure,  more  highly  organized  atoms. 

Every  azotized  constituent  of  the  animal  or  vegetable  organism 
runs  spontaneously  into  putrefaction,  when  exposed  to  moisture 
and  a  high  temperature. 

Azotized  matters  are,  accordingly,  the  only  causes  of  fermen- 
tation and  putrefaction  in  vegetable  substances. 

Putrefaction,  on  account  of  its  defects,  as  a  mixed  transforma- 
tion of  many  different  substances,  may  be  classed  w  ith  the  most 
powerful  processes  of  deoxidation,  by  which  the  strongest  affini^^ 
ties  are  overcome. 

When  a  solution  of  gypsum  in  water  is  mixed  with  a  decoc- 
tion of  sawdust,  or  any  other  organic  matter  capable  of  putrefac- 
tion, and  preserved  in  well-closed  vessels,  it  is  found  after  some 
time,  that  the  solution  no  longer  contains  sulphuric  acid,  but  in 
its  place  carbonic  and  free  hydrosulphuric  acids,  between  which 
the  lime  of  the  gypsum  is  shared.  In  stagnant  water  containing 
sulphates  in  solution,  crystallized  pyrites  are  observed  to  form  on 
the  decaying  roots. 

Now  we  know  that  in  the  putrefaction  of  wood  under  water, 
when  air  therefore  is  excluded,  a  part  of  its  carbon  combines  with 
the  oxygen  of  the  water,  as  well  as  with  the  oxygen  which  the 
wood  itself  contains ;  whilst  its  hydrogen  and  that  of  the  decom- 
posed water  are  liberated  either  in  a  pure  state,  or  as  carburetted 
hydrogen. 

It  is  evident,  that  if  M'ith  the  water  a  substance  containing  a 
jarge  quantity  of  oxygen,  such  as  sulphuric  acid,  be  also  present, 
the  matters  in  the  state  of  putrefaction  will  make  use  of  the  oxy 


S94  YEAST  OR  FERMENT. 


gen  of  that  substance  as  well  as  that  of  the  water,  in  order  to  form 
carbonic  acid  ;  and  the  sulphur  and  hydrogen  being  set  free  will 
combine  whilst  in  the  nascent  state,  producing  hydrosulphurio 
acid,  which  will  be  again  decomposed  if  metallic  oxides  be 
present ;  and  the  results  of  this  second  decomposition  will  be 
water  and  metallic  sulphurets. 

The  putrefied  leaves  of  woad  (Insatis  tinctoria),  in  contact  with 
indigo-blue,  water,  and  alkalies,  suffer  further  decomposition,  and 
the  indigo  is  deoxidized  and  dissolved. 

The  mannite  formed  by  the  putrefaction  of  the  juice  of  the  beet- 
root and  other  plants  containing  sugar,  contains  the  same  number 
of  equivalents  of  carbon  and  hydrogen  as  the  sugar  of  grapes,  but 
two  atoms  less  of  oxygen  ;  and  it  is  highly  probable  that  it  is  pro- 
duced from  sugar  of  grapes,  contained  in  those  plants,  in  precisely 
the  same  manner  as  indigo-blue  is  converted  into  deoxidized 
white  indigo. 

During  the  putrefaction  of  gluten,  carbonic  acid  and  pure  hy- 
drogen gases  are  evolved  ;  phosphate,  acetate,  caseate,  and  lactate 
of  ammonia  being  at  the  same  time  produced  in  such  quantity, 
that  the  further  decomposition  of  the  gluten  ceases.  But  when 
the  supply  of  water  is  renewed,  the  decomposition  begins  again, 
and  in  addition  to  the  salts  just  mentioned,  carbonate  of  ammonia 
and  a  white  crystalline  micaceous  matter  (caseous  oxide)  are 
formed,  together  with  hydrosulphate  of  ammonia,  and  a  mucila- 
ginous substance  coagulable  by  chlorine.  Lactic  acid  is  almost 
always  produced  by  the  putrefaction  of  organic  bodies. 

We  may  now  compare  fermentation  and  putrefaction  with  the 
decomposition  which  organic  compounds  suffer  under  the  influence 
of  a  high  temperature.  Dry  distillation  would  appear  to  be  a 
process  of  combustion  or  oxidation  going  on  in  the  interior  of  a 
substance,  in  which  a  part  of  the  carbon  unites  with  all  or  part 
of  the  oxygen  of  the  compound,  while  other  new  compounds  con- 
taining a  large  proportion  of  hydrogen  are  necessarily  produced. 
Fermentation  may  be  considered  as  a  process  of  combustion  or 
oxidation  of  a  similar  kind,  taking  place  in  a  liquid  between  the 
elements  of  the  same  matter,  at  very  slightly  elevated  temperature  ; 
and  putrefaction  as  a  process  of  oxidation,  in  which  the  oxygen 
of  all  the  substances  present  comes  into  play. 


EREMACAUSIS,  OR  DECAY.  299 


CHAPTER  VL 

Blremacausis,  or  Decay. 

In  organic  nature,  besides  the  processes  of  decomposition  named 
fermentation  and  putrefaction,  another  and  not  less  striking  class 
of  changes  occurs,  which  bodies  suffer  from  the  influence  of  the 
air.  This  is  the  act  of  gradual  combination  of  the  combus- 
tible elements  of  a  body  with  tlie  oxygen  of  the  air ;  a  slow 
combustion  or  oxidation,  to  which  we  shall  apply  the  term  of 
eremacausis. 

The  conversion  of  wood  into  humus,  the  formation  of  acetic 
acid  out  of  alcohol,  nitrification,  and  numerous  other  processes^ 
are  of  this  nature.  Vegetable  juices  of  every  kind,  parts  of  ani- 
mal and  vegetable  substances,  moist  sawdust,  blood,  &c.,  cannot 
be  exposed  to  the  air,  without  suffering  immediately  a  progressive 
change  of  color  and  properties,  during  which  oxygen  is  absorbed. 
These  changes  do  not  take  place  when  water  is  excluded,  or  when 
the  substances  are  exposed  to  the  temperature  of  32°,  and  it  has 
been  observed  that  different  bodies  require  different  degrees  of 
heat,  in  order  to  effect  the  absorption  of  oxygen,  and,  conse- 
quently, their  eremacausis.  The  tendency  to  undergo  this 
change  is  possessed  in  the  highest  degree  by  substances  contain- 
ing nitrogen. 

When  vegetable  juices  are  evaporated  by  a  gentle  heat  in  the 
air,  a  brown  or  brownish-black  substance  is  precipitated  as  a  pro- 
duct of  the  action  of  oxygen  upon  them.  This  substance,  which 
appears  to  possess  similar  properties  from  whatever  juice  it  is  ob- 
tained, has  received  the  name  o^  extractive  matter  ;  it  is  insoluble 
or  very  sparingly  soluble  in  water,  but  is  dissolved  with  facility 
by  alkalies.  By  the  action  of  air  on  solid  animal  or  vegetable 
matters,  a  similar  pulverulent  brown  substance  is  formed,  and  is 
known  by  the  name  of  htimus. 


S9«  EREMACAUSIS,  OR  DECAY; 

The  conditions  which  determine  the  commencement  of  erema* 
causis  are  of  various  kinds.  Many  organic  substances,  par- 
ticularly such  as  are  mixtures  of  several  more  simple  matters, 
oxidize  in  the  air  when  simply  moistened  with  water ;  others  not 
until  they  are  subjected  to  the  action  of  alkalies  ;  but  the  greatest 
part  of  them  undergo  this  state  of  slow  combustion  or  oxidation, 
when  brought  in  contact  with  other  matters  already  in  a  state 
of  decay. 

The  eremacausis  of  an  organic  matter  is  retarded  or  completely 
arrested  by  all  those  substances  which  prevent  fermentation  or 
putrefaction.  Mineral  acids,  salts  of  mercury,  aromatic  sub- 
stances, empyreumatic  oils,  and  oil  of  turpentine,  possess  a  simii. 
lar  action  in  this  respect.  The  latter  substances  have  the  same 
eifect  on  decaying  bodies  as  on  phosphuretted  hydrogen,  the  spon- 
taneous inflammability  of  which  they  destroy. 

Many  bodies  which  do  not  decay  when  moistened  with  water, 
enter  into  eremacausis  when  in  contact  with  an  alkali.  Gallic 
acid,  hsematin,  and  many  other  compounds,  may  be  dissolved  in 
water  and  yet  remain  unaltered  ;  but  if  the  smallest  quantity  of  a 
free  alkali  is  present,  they  acquire  the  property  of  attracting  oxy- 
gen, and  are  converted  into  a  brown  substance  like  humus,  evol- 
ving very  frequently  at  the  same  time  carbonic  acid.  (Chevreul.) 

A  very  remarkable  kind  of  eremacausis  takes  place  in  many 
vegetable  substances,  when  they  are  exposed  to  the  influence  of 
air,  water,  and  ammonia.  They  absorb  oxygen  very  rapidly,  and 
form  splendid  violet  or  red-colored  liquids,  as  in  the  case  of  orcin 
and  erythrin.  They  now  contain  an  azotized  substance,  not  in 
the  form  of  ammonia. 

All  these  facts  show  that  the  action  of  oxygen  seldom  affects 
the  carbon  of  decaying  substances,  and  this  corresponds  exactly 
to  what  happens  in  combustion  at  high  temperatures.  It  is  well 
known,  for  example,  that  when  no  more  oxygen  is  admitted  to  a 
compound  of  carbon  and  hydrogen  than  is  sufficient  to  combine 
with  its  hydrogen,  the  carbon  is  not  burned,  but  is  separated  as 
lamp-black  ;  while,  if  the  quantity  of  oxygen  is  not  sufficient  even 
to  consume  all  the  hydrogen,  new  compounds  are  formed,  such 
M  naphthalin  and  similar  matters,  which  contain  a  smaller  pro. 


EXAMPLES  OF.  397 


portion  of  hydrogen  than  those  compounds  of  carbon  and  hydrogen 
which  previously  existed  in  the  combustible  substance,    'i^-'-'^w" 

There  is  no  example  of  carbon  combining  directly  with  oxygeli 
at  common  temperatures,  but  numerous  facts  show  that  hydrogen, 
in  certain  states  of  condensation,  possesses  that  property.  Lamp- 
black which  has  been  heated  to  redness  may  be  kept  in  contact 
with  oxygen  gas,  without  forming  carbonic  acid  ;  but  lamp-black, 
impregnated  with  oils  contgiining  a  large  proportion  of  hydrogen, 
gradually  becomes  warm,  and  inflames  spontaneously.  The 
spontaneous  inflammability  of  the  charcoal  used  in  the  fabrication 
of  gunpowder  has  been  correctly  ascribed  to  the  hydrogen  con- 
tained in  it  in  considerable  quantity ;  for  during  its  reduction  to 
powder,  no  trace  of  carbonic  acid  can  be  detected  in  the  air 
surrounding  it;  it  is  not  formed  until  the  temperature  of  the 
mass  has  reached  a  red  heat.  The  heat  which  produces  the 
inflammation  is  therefore  not  caused  by  the  oxidation  of  the 
carbon.  i&  i {<>•:: 

The  matters  subject  to  eremacatisis  may  be  divided  into  two 
classes.  The  first  class  comprehends  those  substances  which 
unite  with  the  oxygen  of  the  air,  without  evolving  carbonic  acid ; 
and  the  second,  such  as  emit  carbonic  acid  while  they  absorb 
oxygen,  •  .mairry  ti-T  r - : >. .  r ij  .txis.iiH4tJ>  vif'  -nib  rid   ,f;^Uis  £w«*\A9  9<J1 

When  the  ofl  of  bitter  almonds  is  exposed  to  thd  air,  it  atsdft^ 
two  equivalents  of  oxygen,  and  is  converted  into  benzoic  acid  ^ 
but  half  of  the  oxygen  absorbed  combines  with  the  hydrogen  of 
the  oil,  and  forms  water,  which  remains  in  union  with  the  anhy- 
drous benzoic  acid. 

According  to  the  experiments  of  Dobereiner,  100  parts  of 
pyrogallic  acid  absorb  38*09  parts  of  oxygen  when  in  contact 
with  ammonia  and  water;  the  acid  being  changed  in  conse- 
quence of  this  absorption  into  a  mouldy  substance,  which  contains 
less  oxygen  than  the  acid  itself.  It  is  evident  that  the  substance 
formed  is  not  a  higher  oxide  ;  and  it  is  found,  on  comparing  the 
quantity  of  the  oxygen  absorbed  with  that  of  the  hydrogen  con- 
tained ill  the  acid,  that  they  ai*e  exactly  in  the  proportions  for 
forming  water. 

When  colorless  orcin  is  exposed  together  with  ammonia  to  thft 
contact  of  oxygen  gas,  the  beautiful  red-colored  orcein  is  produe» 
14* 


SOS  EREMACAUSIS,  OR  DECAY. 


-ed.  Now,  the  only  changes  which  take  place  here  are,  that  the 
absorption  of  oxygen  by  the  elements  of  orcin  and  ammonia 
causes  the  formation  of  water  ;  1  equivalent  of  orcin  Ci,  H,  | 
Oj,  and  1  equivalent  of  ammonia  NHj,  absorb  5  equivalents 
of  oxygen,  and  5  equivalents  cf  water  are  produced,  the  compo- 
sition of  orcein  being  Cjg  H,  O^  N.  (Dumas.)  In  this  case 
it  is  evident,  that  the  oxygen  absorbed  has  united  merely  with 
the  hydrogen. 

But,  although  it  appears  very  probable  that  the  oxygen  acts 
primarily  and  principally  upon  hydrogen,  the  most  combustible 
constituent  of  organic  matter  in  the  state  of  decay ;  still  it  can- 
not thence  be  concluded  that  the  carbon  is  quite  devoid  of  the 
power  to  unite  with  oxygen,  when  every  particle  of  it  is  surround- 
ed with  hydrogen,  an  element  with  which  the  oxygen  combines 
with  greater  facility. 

We  know,  on  the  contrary,  that  although  nitrogen  cannot  be 
made  to  combine  with  oxygen  directly,  yet  it  is  oxidized  and 
forms  nitric  acid,  when  mixed  with  a  large  quantity  of  hydrogen, 
and  burned  in  oxygen  gas.  In  this  case  its  affinity  is  evidently 
increased  by  the  combustion  of  the  hydrogen,  which  is  in  fact 
communicated  to  it.  It  is  conceivable  that,  in  a  similar  manner, 
the  carbon  may  be  directly  oxidized  in  several  cases,  obtaining 
from  its  contact  with  hydrogen  in  eremacausis  a  property  which 
it  does  not  itself  possess  at  common  temperatures.  But  the 
formation  of  carbonic  acid  during  the  eremacausis  of  bodies  con- 
taining hydrogen,  must  in  most  cases  be  ascribed  to  another  cause. 
It  appears  to  be  formed  in  a  manner  similar  to  the  formation  of 
acetic  acid,  by  the  eremacausis  of  saliculite  of  potash.  This  salt, 
when  exposed  to  a  moist  atmosphere,  absorbs  3  atoms  of  oxygen  ; 
melanic  acid  is  produced,  a  body  resembling  humus,  in  conse- 
quence of  the  formation  of  which,  the  elements  of  1  atom  of 
acetic  acid  are  separated  from  the  saliculous  acid. 

An  alkaline  solution  of  hsematin  being  exposed  to  an  atmo- 
sphere of  oxygen,  0*2  grm.  absorb  28-6  cubic  centimeters  of 
oxygen  gas  in  twenty-four  hours,  the  alkali  acquiring  at  the  same 
time  6  cubic  centimeters  of  carbonic  acid.  (Chevreul.)  But 
^ese  6  cubic  centimeters  of  carbonic  acid  contain  only  an  equal 
volume  of  oxygen,  so  that  it  is  certain  from  this  experiment  that 


FORMATION  OF  CARBONIC    iCID. 


J  of  the  oxygen  absorbed  have  not  united  with  the  carbon.  It  is 
highly  probable,  that  during  the  oxidation  of  the  hydrogen,  a 
portion  of  the  carbon  had  united  with  the  oxygen  contained  in  the 
hsBinatin,  and  had  separated  from  the  other  elements  as  carbonic 
acid. 

The  experiments  of  De  Saussure  upon  the  decay  of  woody 
fibre  show  that  such  a  separation  is  highly  probable.  Moist 
woody  fibre  evolved  one  volume  of  carbonic  acid  for  every 
volume  of  oxygen  which  it  absorbed.  It  has  just  been  mentioned 
that  carbonic  acid  contains  its  own  volume  of  oxygen.  Now, 
woody  fibre  contains  carbon  and  the  elements  of  water,  so  that 
the  result  of  the  action  of  oxygen  upon  it  is  exactly  the  sam& 
as  if  pure  charcoal  had  combined  directly  with  oxygen.  But 
the  characters  of  woody  fibre  show,  that  the  elements  of  water 
are  not  contained  in  it  in  the  form  of  water  ;  for,  were  this  the 
case,  starch,  sugar,  and  gum  must  also  be  considered  as  hydrates 
of  carbon. 

But  if  the  hydrogen  does  not  exist  in  woody  fibre  in  the  form 
of  water,  the  direct  oxidation  of  the  carbon  cannot  be  considered 
as  at  all  probable,  without  rejecting  all  the  facts  established  by 
experiment  regarding  the  process  of  combustion  at  low  tempera- 
tures. 

If  we  examine  the  action  of  oxygen  upon  a  substance  con- 
taining a  large  quantity  of  hydrogen,. such  as  alcohol,  we  find 
most  distinctly,  that  the  direct  formation  of  carbonic  acid  is  the 
last  stage  of  its  oxidation,  and  that  it  is  preceded  by  a  series  of 
changes,  the  last  of  which  is  a  complete  combustion  of  the  hy- 
drogen. Aldehyde,  acetic,  formic,  oxalic,  and  carbonic  acids, 
form  a  connected  chain  of  products  arising  from  the  oxidation  of 
alcohol :  and  the  successive  changes  which  this  fluid  experi- 
ences from  the  action  of  oxygen  may  be  readily  traced  in  them. 
Aldehyde  is  alcohol  minus  hydrogen  ;  acetic  acid  is  formed  by 
the  direct  union  of  aldehyde  with  oxygen.  Formic  acid  and 
water  are  formed  by  the  union  of  acetic  acid  with  oxygen. 
When  all  the  hydrogen  is  removed  from  formic  acid,  oxalic  acid 
is  produced  ;  and  the  latter  acid  is  converted  into  carbonic  acid 
by  uniting  with  an  additional  portion  of  oxygen.  All  these  pro- 
ducts  appear  to  be  formed  simultaneously,  by  the  action  of  oxid* 


300  EREMACAUSIS  OR  DECAY; 


ftsin^  agents  on  aloohcl ;  b»it  it  can  Bcarcely  be  doubted,  that  the 
ferritiatibn  of  the  last  product,  -he  carbonic  acid,  does  not  take 
p'lac^  until  all  the  hydrogen  has  been  abstracted.  ^     "' 

The  absorption  of  oxygen  by  drying  oils  certainly  does  not 
depend  upon  the  oxidation  of  their  carbon  ;  for  in  raw  walnut- 
oil,  for  example,  which  was  not  free  from  mucilage  and  other 
substances,  only  twenty-one  volumes  of  carbonic  acid  were 
formed  for  every  146  volumes  of  O.tygen  gas  absorbed. 

Tt  must  he  remembered,  that  combustion  or  oxidation  at  low 
temperatures  produces  results  quite  similar  to  combustion  at 
high  temperatures  with  limited  access  of  air.  The  most 
combustible  element  of  a  compound  exposed  to  the  action  of 
oxygen,  must  become  oxidized  first,  for  its  superior  combustibility 
is  caused  by  its  being  enabled  to  unite  with  oxygen  at  a  tempera- 
ture at  which  the  other  elements  cannot  enter  into  that  combina- 
tion ;  this  property  having  the  same  eifect  as  a  greater  affinity. 

The  combustibility  of  potassium  is  no  measure  of  its  affinity 
for  oxygen ;  we  have  reason  to  believe  that  the  attraction  of 
magnesium  and  aluminium  for  oxygen  is  greater  than  that  of 
potassium  for  the  same  element;  but  neither  of  those  metals 
oxidizes  either  in  air  or  water  at  common  temperatures,  whilst 
potassium  decomposes  water  with  great  violence,  and  appropriates! 
its  oxygen. 

Phosphorus  and  hydrogen  combine  with  oxygen  at  ordinary 
temperatures,  the  first  in  moist  air,  the  second  when  in  contact 
with  finely-divided  platinum  ;  while  charcoal  requires  a  red  heat 
before  it  can  enter  into  combination  with  oxygen.  It  is  evident 
that  phosphorus  and  hydrogen  are  more  combustible  than  char- 
coal, that  is,  that  their  affinity  for  oxygen  at  common  tempera- 
TURES  is  greater  ;  and  this  is  not  the  less  certain,  because  it  is 
found,  that  carbon  in  certain  other  conditions  shows  a  much 
greater  affinity  for  oxygen  than  either  of  those  substances. 

In  putrefaction,  the  conditions  are  evidently  present,  under 
which  the  superior  affinity  of  carbon  for  oxygen  comes  into 
play  ;  neither  expansion,  cohesion,  nor  the  gaseous  state,  oppostes 
it,  whilst  in  eremacaiisis  all  these  restraints  have  to  be  over, 
come.  ri-.ct?.'aft  . 

The  evolution  of  carbonic  acid;  dtiring  the  decay  or  erenia« 


ITS  CAUSE.  Hi 


causis  of  animal  or  vegetable  bodies  which  are  rich  in  hydrogen, 
must  accordingly  be  ascribed  to  a  transposition  of  the  elements 
or  disturbance  in  their  attractions,  similar  to  that  which  gives 
rise  to  the  formation  of  carbonic  acid  in  the  processes  of  fermen- 
tation and  putrefaction.  While  the  hydrogen  of  the  substance 
is  removed  and  oxidized  by  eremacausis,  carbon  and  oxygen 
separate  from  the  remaining  elements  in  the  form  of  carbonic 
acid. 

The  eremacausis  of  such  substances  is,  therefore,  a  decom- 
position analogous  to  the  putrefaction  of  azotized  bodies.  For  in 
these  there  are  two  affinities  at  play  ;  the  affinity  of  nitrogen  for 
hydrogen,  and  that  of  carbon  for  oxygen,  and  both  facilitate  the 
disunion  of  the  elements.  Now  there  are  two  affinities  also  in 
action  in  those  bodies  which  decay  with  the  evolution  of  carbonic 
acid.  One  of  these  affinities  is  the  attraction  of  the  oxygen  of 
the  air  for  the  hydrogen  of  the  substance,  which  corresponds  to 
the  attraction  of  nitrogen  for  the  same  element  ;  and  the  other  is 
the  affinity  of  the  carbon  of  the  substance  for  its  oxygen,  which 
is  constjant  under  all  circumstances. 

When  wood  putrefies  in  marshes,  carbon  and  oxygen  are 
separated  from  its  elements  in  the  form  of  carbonic  acid,  and 
hydrogen  in  the  form  of  carburetted  hydrogen.  But  when  wood 
decays  or  putrefies  in  the  air,  its  hydrogen  does  not  combine  with 
carbon,  but  with  oxygen,  for  which  it  has  a  much  greater  affinity 
at  common  temperatures. 

Now  it  is  evidently  owing  to  the  complete  similarity  of  these 
processes,  that  decaying  and  putrefying  bodies  can  mutually  re- 
place one  another  in  their  reciprocal  actions. 

All  putrefying  bodies  pass  into  a  state  of  decay  when  exposed 
freely  to  the  air,  and  all  decaying  matters  into  that  of  putrefac- 
tion when  air  is  excluded.  All  bodies,  likewise,  in  a  state  of 
decay  are  capable  of  inducing  putrefaction  in  other  bodies,  in  the 
same  manner  as  putrefying  bodies  themselves  do. 


•a»..  mmt^v^ir  »»^9*:^'  i^,9iniJi  v 


592  EREMACAUSIS  OR  DECAY. 


CHAPTER  VII. 

Eremacausis  or  decay  of  bodies  destitute  of  Nitrogen :  formation  of 
Acetic  Acid. 

All  those  substances  which  appear  to  possess  the  property  of 
entering  spontaneously  into  fermentation  and  putrefaction,  do  not 
in  reality  suffer  those  changes  without  some  previous  disturbance 
in  the  attraction  of  their  elements.  Eremacausis  always  pre- 
cedes fermentation  and  putrefaction,  and  it  is  not  until  after  the 
absorption  of  a  certain  quantity  of  oxygen  that  the  signs  of  a  trans- 
formation in  the  interior  of  the  substances  show  themselves. 

It  is  a  very  general  error  to  suppose  that  organic  substances 
have  the  power  of  undergoing  change  spontaneously,  without  the 
aid  of  an  external  cause.  When  they  are  not  already  in  a  state 
of  change,  it  is  necessary,  before  they  can  assume  that  state,  that 
the  existing  equilibrium  of  their  elements  should  be  disturbed  ; 
and  the  most  common  cause  of  this  disturbance  is  undoubtedly 
the  atmosphere  which  surrounds  all  bodies. 

The  juices  of  the  fruit  or  other  parts  of  a  plant  prone  to  de- 
composition, retain  their  properties  unchanged  as  long  as  they 
are  protected  from  immediate  contact  with  the  air,  that  is,  as 
long  as  the  cells  or  organs  in  which  they  are  contained  resist  the 
influence  of  the  air.  It  is  not  until  after  the  juices  have  been 
exposed  to  the  air,  and  have  absorbed  a  certain  quantity  of 
oxygen,  that  the  substances  dissolved  in  them  begin  to  be  decom- 
posed. 

The  beautiful  experiments  of  Gay-Lussac  upon  the  fermenta- 
tion of  the  juice  of  grapes,  as  well  as  the  important  practical 
improvements  to  which  they  have  led,  are  the  best  proofs  that  the 
atmosphere  possesses  an  influence  upon  the  changes  of  organic 
substances.     The  juice  of  grapes  expressed  under  a  receiver 


OF  BODIES  DESTITUTE  OF  NITROGEN.  308 

filled  with  mercury,  so  that  air  was  completely  excluded,  did  not 
ferment.  But  when  the  smallest  portion  of  air  was  introduced, 
a  certain  quantity  of  oxygen  became  absorbed,  and  fermentation 
immediately  began.  Although  the  juice  was  expressed  from  the 
grapes  in  contact  with  air,  under  the  conditions  therefore  neces- 
sary to  cause  its  fermentation,  still  this  change  did  not  ensue 
when  the  juice  was  heated  in  close  vessels  to  the  temperature  of 
boiling  water.  When  thus  treated,  it  could  be  preserved  for 
years  without  losing  its  property  of  fermenting.  A  fresh  expo- 
sure to  the  air  at  any  period  caused  it  to  ferment. 

Animal  food  of  every  kind,  and  even  the  most  delicate  vege- 
tables, may  be  preserved  unchanged  if  heated  to  the  temperature 
of  boiling  water  in  vessels  from  which  the  air  is  completely  ex- 
cluded. Food  thus  prepared  has  been  kept  for  fifteen  years,  and 
upon  opening  the  vessels  after  this  long  time,  has  been  found  as 
fresh  and  well-flavored  as  when  originally  placed  in  them. 

The  action  of  the  oxygen  in  these  processes  of  decomposition 
is  very  simple  ;  it  excites  changes  in  the  compositiot  of  the 
azotized  matters  dissolved  in  the  juices  ; — the  mode  of  combina- 
tion of  the  elements  of  those  matters  undergoes  a  disturbance 
and  change  in  consequence  of  their  contact  with  oxygen.  The 
oxygen  acts  here  in  a  similar  manner  to  the  friction  or  motion 
which  effects  the  mutual  decomposition  of  two  salts,  the  crystalli- 
zation of  salts  from  their  solution,  or  the  explosion  of  fulminating 
mercury.  It  causes  the  state  of  rest  to  be  vxMiverted  into  a  state 
of  motion. 

When  this  condition  of  intestine  motion  is  once  excited,  the 
presence  of  oxygen  is  no  longer  necessary.  The  smallest  parti- 
cle of  an  azotized  body  in  this  act  of  decomposition  exercises  an 
influence  upon  the  particles  in  contact  with  it,  and  the  state  of 
motion  is  thus  propagated  through  the  substance.  The  air  may 
now  be  completely  excluded,  but  the  fermentation  or  putrefaction 
proceeds  uninterruptedly  to  its  completion. 

Aldehyde  attracts  oxygen  from  the  air,  and,  by  the  process  of 
eremacausis,  becomes  vinegar ;  if  the  air  be  now  excluded,  the 
disturbance  already  begun  is  not  arrested,  but  the  products  are 
very  different.     Two  substances  are  then  formed  by  a  change  in 


304  EREMACAUSIS  OR  DECAY 

the  arrangement  of  the  elements.  Their  composition  is  similari 
but  they  are  very  unlike  in  character. 

The  contact  of  ammonia  and  of  alkalies  in  general  maybe 
mentioned  among  the  chemical  conditions  which  determine  the 
commencement  of  eremacausis  ;  for  their  presence  causes  many 
substances  to  absorb  oxygen  and  to  decay,  in  which  neither 
oxygen  nor  alkalies  alone  produce  that  change. 

Thus  alcohol  does  not  combine  with  the  oxygen  of  the  air  at 
common  temperatures.  But  a  solution  of  potash  in  alcohol  ab- 
sorbs oxygen  with  much  rapidity,  and  acquires  a  brown  color. 
The  alcohol  is  found  after  a  short  time  to  contain  acetic  acid, 
formic  acid,  and  the  products  of  the  decomposition  of  aldehyde 
by  alkalies,  including  the  resin  of  aldehyde,  which  gives  the 
liquid  a  brown  color. 

The  most  general  condition  for  the  production  of  eremacausis 
in  organic  matter  is  contact  with  a  body  already  in  the  state  of 
eremacausis  or  putrefaction.  We  have  here  an  instance  of  true 
contagion  ;  for  the  communication  of  the  state  of  combustion  is 
in  reality  the  effect  of  the  contact. 

It  is  decaying  wood  which  causes  fresh  wood  around  it  to  as- 
sume the  same  condition,  and  it  is  the  very  finely  divided  woody 
fibre  in  the  act  of  decay  which  in  moistened  gall-nuts  converts 
the  tannic  acid  with  such  rapidity  into  gallic  acid. 

A  most  remarkable  and  decided  example  of  this  induction  of 
combustion  has  been  observed  by  De  Saussure.  It  has  already 
been  mentioned,  that  moist  woody  fibre,  cotton,  silk,  or  vegetable 
mould,  in  the  act  of  fermentation  or  eremacausis,  converts  the 
oxygen  gas  surrounding  it  into  carbonic  acid,  without  change  of 
Volume.  Now,  De  Saussure  added  a  certain  quantity  of  hydro- 
gen gas  to  the  oxygen,  and  observed  a  diminution  in  volume 
immediately  after  the  addition.  A  part  of  the  hydrogen  gas  had 
disappeared,  and  along  with  it  a  portion  of  the  oxygen,  but  a  cor- 
responding quantity  of  carbonic  acid  gas  had  not  been  formed. 
The  hydrogen  and  oxygen  had  disappeared  in  exactly  the 
same  proportion  as  that  in  which  they  combine  to  form  water ; 
a  true  combustion  of  the  hydrogen,  therefore,  had  been  induced 
by  mere  contact  with  matter  in  the  state  of  eremacausis.  Thfe 
action  of  the  decaying  substance  here  produced  results  exactly 


OF  BODIES  DESTITUTE  OF  NITROGEN.  305 


similar  to  those  effected  by  spongy  platinum  ;  but  that  they  pro- 
ceeded from  a  different  cause  was  shown  by  the  fact  that  the 
presence  of  carbonic  oxide,  which  arrests  completely  the  action 
of  platinum  on  a  mixture  of  oxygen  and  hydrogen,  did  not  re- 
tard in  the  slightest  degree  the  combustion  of  the  hydrogen  in 
contact  with  the  decaying  bodies. 

But  t)\e  same  bodies  were  found  by  De  Saussure  not  to  pos- 
sess the  property  just  described,  before  they  were  in  a  state  of 
fermentation  or  decay ;  and  he  has  shown  that  even  when  they 
are  in  this  state,  the  presence  of  antiseptic  matter  destroys  com- 
pletely all  their  influence. 

Let  us  suppose  a  volatile  substance  containing  a  large  quanti- 
ty of  hydrogen  to  be  substituted  for  the  hydrogen  gas  in  Dc 
Saussure's  experiments.  Now,  the  hydrogen  in  such  compounds 
being  contained  in  a  state  of  greater  condensation  would  suffer 
a  more  rapid  oxidation,  that  is,  its  con^ustion  would  be  sooner 
completed.  This  principle  is  in  reality  attended  to  in  the  manu- 
factories in  which  acetic  acid  is  prepared  according  to  the  new 
plajn.  In  the  process  there  adopted  all  the  conditions  are  afforded 
for  the  eremacausis  of  alcohol,  and  for  its  consequent  conversion 
into  acetic  acid. 

The  alcohol  is  exposed  to  a  moderate  heat,  and  spread  over  a 
very  extended  surface,  but  these  conditions  are  not  sufficient  to 
effect  its  oxidation.  The  alcohol  must  either  be  in  contact  with 
decaying  wood,  or  must  contain  a  substance  which  is  with  facility 
changed  by  the  oxygen  of  the  air,  and  either  enters  into  erema- 
causis by  mere  contact  with  oxygen,  or  by  its  fermentation  or 
putrefaction  yields  products  possessed  of  this  property.  A  small 
quantity  of  beer,  acescent  wine,  a  decoction  of  malt,  honey,  and 
numerous  other  substances  of  this  kind,  possess  the  action 
desired. 

The  difference  in  the  nature  of  the  substances  possessing  this 
property  shows,  that  none  of  them  can  contain  a  peculiar  matter 
which  has  the  property  of  exciting  eremacausis  ;  they  are  only 
the  bearers  of  an  action,  the  influence  of  which  extends  beyond 
the  sphere  of  their  own  attractions.  Their  power  consists  in  a 
condition  of  decomposition  or  eremacausis,  which  impresses  the 
same  condition  upon  the  atoms  of  alcohol  in  its  vicinity  j  exactly 


806  EREMACAUSIS  OR  DECAY 

as  in  the  case  of  an  alloy  of  platinum  and  silver  dissolving  in 
nitric  acid,  in  which  the  platinum  becomes  oxidized  by  virtue  of 
an  inductive  action  exercised  upon  it  by  the  silver  in  the  act  of 
its  oxidation.  In  the  preparation  of  vinegar,  the  hydrogen  of 
alcohol,  with  the  formation  of  water  and  evolution  of  heat,  is 
oxidized  at  the  expense  of  the  oxygen  in  contact  with  it ;  the 
residue  is  aldehyde,  a  substance  possessing  as  great  an  affinity 
for  oxygen  as  sulphurous  acid,  and  by  uniting  directly  with  the 
latter,  it  produces  acetic  acid. 


OF  BODIES  CONTAINING  NITROGEN.  807 


CHAPTER  VIII. 

Eremacausis  of  Substances  containing  Nitrogen :  Nitrification. 

When  azotized  substances  are  burned  at  high  temperatures,  their 
nitrogen  does  not  enter  into  direct  combination  with  oxygen. 
The  knowledge  of  this  fact  is  of  assistance  in  considering  the 
process  of  the  eremacausis  of  such  substances.  Azotized  organic 
matter  always  contains  carbon  and  hydrogen,  both  of  which 
elements  have  a  very  strong  affinity  for  oxygen. 

Now  nitrogen  possesses  a  very  feeble  affinity  for  oxygen,  so 
that  it  is  placed,  in  regard  to  that  element,  in  a  position  similar 
lo  that  of  the  carbon  of  bodies  containing  much  hydrogen  during 
their  combustion  ;  a  separation  of  the  carbon  of  the  latter  sub- 
stances in  an  uncombined  state  takes  place,  and  in  the  same  way 
the  substances  containing  nitrogen  give  out  that  element  in  its 
gaseous  form. 

When  moist  azotized  animal  matter  is  exposed  to  the  action 
of  air,  ammonia  is  constantly  liberated  ;  nitric  acid  is  never 
formed  under  these  circumstances. 

But  when  alkalies  or  alkaline  bases  are  present,  a  union  of 
oxygen  with  the  nitrogen  takes  place  under  the  same  circum- 
stances, and  nitrates  are  formed  together  with  the  other  products 
of  oxidation. 

Although  we  see  the  most  simple  means  and  direct  methods 
employed  in  the  great  processes  of  decomposition  occurring  in 
nature,  still  we  find  that  the  final  result  depends  on  a  succession 
of  actions,  which  are  essentially  influenced  by  the  chemical 
nature  of  the  bodies  submitted  to  decomposition. 

When  it  is  observed  that  the  character  of  a  substance  remains 
unaltered  in  a  whole  series  of  phenomena,  there  is  no  reason  to 


ms  EREMACAUSIS  OR  DECAY 


ascribe  a  new  character  to  it,  for  the  purpose  of  explaining  a  sin- 
gle  phenomenon,  especially  where  the  explanation  of  that, 
according  to  known  facts,  offers  no  difficulty. 

The  most  distinguished  philosophers  suppose  that  the  nitrogen 
in  an  animal  substance,  when  exposed  to  the  action  of  air, 
water,  and  alkaline  bases,  possesses  the  power  of  combining 
directly  with  oxygen,  and  of  thus  forming  nitric  acid ;  but  we 
are  not  acquainted  with  a  single  fact  which  justifies  this  opinion. 
It  is  only  by  the  interposition  of  a  large  excess  of  hydrogen  in 
the  state  of  combustion  or  oxidation,  that  nitrogen  can  be  con- 
verted into  an  oxide. 

When  a  compound  of  nitrogen  and  carbon,  such  as  cyanogen, 
is  burned  in  oxygen  gas,  its  carbon  alone  is  oxidized  ;  and  when 
it  is  conducted  over  a  metallic  oxide  heated  to  redness,  an  oxide 
of  nitrogen  is  very  rarely  produced,  and  never  when  the  carbon 
is  in  excess.  Kuhlmann  found  in  his  experiments,  that  it  was 
only  when  cyanogen  was  mixed  with  an  excess  of  oxygen  gas, 
and  conducted  over  spongy  platinum,  that  nitric  acid  was  gene- 
rated. 

Kuhlmann  could  not  succeed  in  causing  pure  nitrogen  to  conN 
bine  directly  with  oxygen,  even  under  the  most  favorable  cir- 
stances ;  thus,  with  the  aid  of  spongy  platinum  at  different  tem- 
peratures, no  union  took  place. 

The  carbon  in  the  cyanogen  gas  must,  therefore,  have  given 
rise  to  the  combustion  of  the  nitrogen  by  induction. 

On  the  other  hand,  we  find  that  ammonia  (a  compound  of  hy- 
drogen and  nitrogen)  cannot  be  exposed  to  the  action  of  oxygen, 
without  the  formation  of  an  oxide  of  nitrogen,  and  production  of 
nitric  acid,  in  consequence  of  this  union. 

It  is  owing  to  the  great  facility  with  which  ammonia  is 
converted  into  nitric  acid,  that  it  is  so  difficult  to  obtain  a  cor- 
rect determination  of  the  quantity  of  nitrogen  in  a  compc«*imd 
subjected  to  analysis,  in  which  it  is  either  contained  in  the  form 
of  ammonia,  or  from  which  ammonia  is  formed  by  an  elevation 
of  temperature.  For  when  ammonia  is  passed  over  the  red-hot 
oxide  of  copper,  it  is  converted,  either  completely  or  partially, 
into  binoxide  of  nitrogen. 

When  ammoniacal  gas  is  conducted  over  peroxide  of  manga- 


OF  BODIES  CONTAINING  NITROGEN.  309 

nese  or  iron  heated  to  redness,  a  large  quantity  of  nitrate  of  am- 
monia is  obtained,  if  the  ammonia  be  in  excess  ;  and  the  same 
decomposition  happens  when  ammonia  and  oxygen  are  together 
passed  over  red-hot  spongy  platinum. 

It  appears,  therefore,  that  the  combination  of  oxygen  with 
nitrogen  occurs  rarely  during  the  combustion  of  compounds  of 
the  latter  element  with  carbon,  but  that  nitric  acid  is  always  a 
product  when  ammonia  is  present  in  the  substance  exposed  to 
oxidation. 

The  cause  wherefore  the  nitrogen  in  ammonia  exhibits  such 
a  strong  disposition  to  become  converted  into  nitric  acid  is  un- 
doubtedly that  the  two  products,  which  are  the  result  of  the  oxi- 
dation of  the  constituents  of  ammonia,  possess  the  power  of  unit- 
ing with  one  another.  Now  this  is  not  the  case  in  the  combus- 
tion of  compounds  of  carbon  and  nitrogen ;  here  one  of  the  pro- 
ducts is  carbonic  acid,  which,  on  account  of  its  gaseous  form, 
must  oppose  the  combination  of  the  oxygen  and  nitrogen,  by 
preventing  tlieir  mutual  contact,  while  the  superior  affinity  of  its 
carbon  for  the  oxygen  during  the  act  of  its  formation  will  aid 
this  effect.  »?iV^  ^oi; 

When  sufficient  access  of  air  is  admitted  during  the  combus- 
tion of  ammonia,  water  is  formed  as  well  as  nitric  acid,  and  both 
of  these  bodies  combine  together.  The  presence  of  water  may, 
indeed,  be  considered  as  one  of  the  conditions  essential  to  nitrifi- 
cation, since  nitric  cannot  exist  without  it. 

Eremacausis  is  a  kind  of  putrefaction,  differing  from  the  com- 
mon process  of  putrefaction,  only  in  the  part  which  the  oxygen 
of  the  air  plays  in  the  transformations  of  the  body  in  decay. 
When  this  is  remembered,  and  when  it  is  considered  that  in  the 
transposition  of  the  elements  of  azotized  bodies  their  nitrogen 
always  assumes  the  form  of  ammonia,  and  that  in  this  form  nitro- 
gen possesses  a  much  greater  disposition  to  unite  with  oxygen 
than  it  has  in  any  of  its  other  compounds  ;  we  can  with  difficulty 
resist  the  conclusion,  that  ammonia  is  the  source  of  the  formation 
of  nitric  acid  on  the  surface  of  the  earth. 

Azotized  animal  matter  is  not,  therefore,  the  immediate  cause 
of  nitrification ;  it  contributes  to  the  production  of  nitric  acid 


$lt  EREMACAUSIS  OR  DECAY. 

only  in  so  far  as  it  is  a  slow  and  continued  source  of  am- 
monia.* 

Now  it  has  been  shown  in  the  former  part  of  this  work,  that 
ammonia  is  always  present  in  the  atmosphere,  so  that  nitrates 
might  thence  be  formed  in  substances  which  themselves  con- 
tained no  azotized  matter.  It  is  known  also,  that  porous  sub- 
stances possess  generally  the  power  of  condensing  ammonia  ; 
there  are  few  ores  of  iron  which  do  not  evolve  ammoniacal  pro- 
ducts when  heated  to  redness,  and  ammonia  is  the  cause  of  the 
peculiar  smell  perceived  upon  moistening  aluminous  minerals. 
Thus,  ammonia,  by  being  a  constituent  of  the  atmosphere,  is  a 
very  widely  diffused  cause  of  nitrification,  which  will  come  into 
play  whenever  the  different  conditions  necessary  for  the  oxida- 
tion of  ammonia  are  combined.  It  is  probable  that  other  orga- 
nic bodies  in  the  state  of  eremacausis  are  the  means  of  causing 
the  combustion  of  ammonia ;  at  all  events,  the  cases  are  very 
rare  in  which  nitric  acid  is  generated  from  ammonia,  in  the  ab- 
sence of  all  matter  capable  of  eremacausis. 

From  the  preceding  observations  on  the  causes  of  fermenta- 
tion, putrefaction,  and  decay,  we  may  now  draw  several  conclu- 
sions calculated  to  correct  the  views  generally  entertained  re- 
specting the  fermentation  of  wine  and  beer,  and  several  other 
important  processes  of  decomposition  occurring  in  nature. 

*  According  to  the  observations  of  Collard  de  Martigny,  ammonia  if 
converted  directly  into  nitric  acid  when  in  contact  with  hydrate  of  lime 
and  with  air,  without  the  intervention  of  any  decaying  substance. 


YEAST  FROM  BEER  AND  WINE.  311 


CHAPTER  IX. 

On  Vinous  Fermentation  : — Wine  and  Beer. 

It  has  already  been  mentioned  that  fermentation  is  excited  in  the 
juice  of  grapes  by  the  access  of  air ;  alcohol  and  carbonic  acid 
being  formed  by  the  decomposition  of  the  sugar  contained  in  the 
fluid.  But  it  was  also  stated,  that  the  process  once  commenced, 
continues  until  all  the  sugar  is  completely  decomposed,  quite 
independently  of  any  further  influence  of  the  air. 

In  addition  to  the  alcohol  and  carbonic  acid  formed  by  the  fer- 
mentation of  the  juice,  there  is  also  produced  a  yellow  or  grey 
insoluble  substance,  containing  a  large  quantity  of  nitrogen.  It 
is  this  body  which  possesses  the  power  of  inducing  fermentation 
in  a  new  solution  of  sugar,  and  which  has  in  consequence  re- 
ceived the  name  o^  ferment. 

The  alcohol  and  carbonic  acid  are  produced  from  the  elements 
of  the  sugar,  and  the  ferment  from  those  azotized  constituents  of 
the  juice  termed  gluten  or  vegetable  albumen. 

According  to  the  experiments  of  De  Saussure,  fresh  impure 
gluten  evolved,  in  five  weeks,  twenty-eight  times  its  volume  of  a 
gas  which  consisted  of  J  of  carbonic  acid,  and  J  of  pure  hydro- 
gen gas  ;  ammoniacal  salts  of  several  organic  acids  were  formed 
at  the  same  time.  Water  must,  therefore,  be  decomposed  during 
the  putrefaction  of  gluten  ;  the  oxygen  of  this  water  must  enter 
into  combination  with  some  of  its  constituents,  whilst  hydrogen 
is  liberated,  a  circumstance  which  happens  only  in  decomposi- 
tions of  the  most  energetic  kind.  Neither  ferment,  nor  any 
substance  similar  to  it,  is  formed  in  this  case  ;  and  we  have  seen 
that  hydrogen  is  not  evolved  in  the  fermentation  of  saccharine 
vegetable  juices. 

It  is  evident  that  the  decomposition  which  gluten  suffers  in  an 
isolated  state,  and  that  which  it  undergoes  when  dissolved  in  a 


312  '    ViN(m§  ftlMEfl^T^rfo^. ' 

vegetable  juice,  belong  to  two  different  kinds  of  transformations. 
There  is  reason  to  believe  that  its  change  to  the  insoluble  state 
depends  upon  an  absorption  of  oxygen,  for  its  separation  in  this 
state  may  be  effected,  under  certain  conditions,  by  free  exposure 
to  the  air,  without  the  presence  of  fermenting  sugar.  It  is  known 
also  that  the  juice  of  grapes,  or  vegetable  juices  in  general,  be- 
come turbid  when  in  contact  with  air,  before  fermentation  com- 
mences ;  and  this  turbidity  is  owing  to  the  formation  of  an 
insoluble  precipitate  of  the  same  nature  as  ferment. 

From  the  phenomena  observed  during  the  fermentation  of  wort,"* 
it  is  known  with  perfect  certainty  that  ferment  is  formed  from 
gluten  at  the  same  time  that  the  transformation  of  the  sugar  is 
effected ;  for  the  wort  contains  the  azotized  matter  of  the  corn, 
namely,  gluten  in  the  same  condition  as  it  exists  in  the  juice  of* 
grapes.  The  wort  ferments  by  the  addition  of^  yeast,  but  after  its 
decomposition  is  completed,  the  quantity  of  ferment  or  yeast  is 
found  to  be  thirty  times  greater  than  it  originally  was. 

Yeast  from  beer  and.  that  from  wine,  examined  under  the  mi- 
croscope, present  the  same  form  and  general  appearance.  They 
are  both  acted  on  in  the  same  manner  by  alkalies  and  by  acids, 
and  possess  the  power  of  inducing  fermentation  anew  in  a  solution 
of  sugar;  in  short,  they  must  be  considered  as  identical. 

The  fact  that  water  is  decomposed  during  the  putrefaction  of 
gluten,  has  been  completely  proved.  The  tendency  of  the  carbon 
of  the  gluten  to  appropriate  the  oxygen  of  water  must  therefore 
always  be  in  action,  whether  the  gluten  is  decomposed  in  a  soluble 
or  insoluble  state.  These  considerations,  therefore,  as  well  as 
the  circumstance  which  all  the  experiments  made  on  this  subject 
appear  to  point  out,  that  the  conversion  of  gluten  to  the  insoluble 
state  is  the  result  of  oxidation,  lead  us  to  conclude  that  the  oxy^ 
gen  consumed  in  this  process  is  derived  from  the  elements  of 
water,  or  from  the  sugar  which  contains  oxygen  and  hydrogen  in 
the  same  proportion  as  water.  At  all  events,  the  oxygen  thus 
consumed  in  the  fermentation  of  wine  and  beer  is  not  taken  from 
the  atmosphere. 

0/5   ■■'''  ''■'■  ■     '      -■•       •■•■    ■    ■    ;      '  .:-,...     .. 

,.  *  Wort  is  an  infusion  of  malt;  it  consists  of  the  soluble  parts  o^, ^iiyi* 
substance  dissolved  in  water. 


OILY  AND  ETHEREAL  PRODUCTS.  313 


The  fermentation  of  pure  sugar  in  contact  with  yeast  must  evi- 
dently be  a  very  different  process  from  the  fermentation  of  wort 
or  of  must* 

In  the  former  case,  the  yeast  disappears  during  the  decompo- 
sition of  sugar ;  but  in  the  latter,  a  transformation  of  gluten 
is  effected  at  the  same  time,  by  which  ferment  is  generated. 
Thus  yeast  is  destroyed  in  the  one  case,  but  is  formed  in  the 
other. 

Now,  since  no  free  hydrogen  gas  can  be  detected  during  the 
fermentation  of  beer  and  wine,  it  is  evident  that,  since  the  oxida- 
tion of  the  gluten,  that  is,  its  conversion  into  ferment,  must  take 
place  at  the  cost  either  of  the  oxygen  of  the  water,  or  of  that  of 
the  sugar;  either  the  hydrogen  liberated  must  enter  into  new 
combinations,  or  by  the  dcoxidation  of  the  sugar,  new  compounds 
containing  a  large  proportion  of  hydrogen,  and  small  quantity  of 
oxygen,  together  with  the  carbon  of  the  sugar,  must  be  formed. 

It  is  well  known  that  wine  and  fermented  liquors  generally 
contain,  in  addition  to  the  alcohol,  other  substances  which  could 
not  be  detected  before  their  fermentation,  and  which  must  have 
been  formed,  therefore,  during  that  process,  in  a  manner  similar 
to  the  production  of  mannite.  The  smell  and  taste  distinguishing 
wine  from  all  other  fermented  liquids  are  known  to  depend  upon 
an  ether  of  a  volatile  and  highly  combustible  acid  ;  the  ether  is 
of  an  oily  nature,  and  has  received  the  name  CEnanthic  ether. 
It  is  also  ascertained  that  tiie  smell  and  taste  of  brandy  from  corn 
and  potatoe  are  owing  to  a  peculiar  oil,  the  oil  of  potatoe  spirit 
This  oil  is  more  closely  allied  to  alcohol  in  its  properties,  than  to 
any  other  organic  substance. 

These  bodies  are  })roducts  of  tlie  deoxidation  of  the  substances 
dissolved  in  the  fermenting  liquids ;  they  contain  less  oxygen 
than  sugar  or  gli.'en.  but  are  remarkable  for  their  large  propor- 
tion of  hydrogen. 

CEnanthic  acid  contains  an  equal  number  of  equivalents  of 
carbon  and  hydrogen,  exactly  the  same  proportions  of  these 
elements,  therefore,  as  sugar,  but  by  no  means  the  same  pro- 
portion of  oxygen.  The  oil  of  potatoes  contains  much  more 
hy4r(^en. 

*  The  liquid  expressed  from  grapes  when  fully  ripe  is  called  rnuit 
15 


314  VINOUS  FERMENTATION. 


Although  it  cannot  be  doubted  that  these  volatile  liquids  are 
formed  by  a  mutual  interchange  of  the  elements  of  gluten  and  of 
sugar,  in  consequence,  therefore,  of  a  true  process  of  putrefac- 
tion, still  it  is  certain,  that  other  causes  exercise  an  influence 
upon  their  production  and  peculiarities. 

The  substances  in  wine  to  which  its  taste  and  smell  are  owing, 
are  generated  during  the  fermentation  of  the  juice  of  such  grapes 
as  contain  a  certain  quantity  of  tartaric  acid  ;  they  are  not  found 
in  wines  free  from  all  acid,  or  which  contain  a  different  organic 
acid,  such  as  acetic  acid. 

The  wines  of  warm  climates  possess  no  odor ;  wines  grown  in 
France  have  it  in  a  marked  degree,  but  in  the  wines  from  the 
Rhine  the  perfume  is  most  intense.  The  kinds  of  grapes  on  the 
Rhine,  which  ripen  very  late,  and  scarcely  ever  completely,  such 
as  the  RiESSLTNG  and  Orleans,  have  the  strongest  perfume  or 
bouquet,  and  contain,  proportionally,  a  larger  quantity  of  tartaric 
acid.  The  wines  from  the  earlier  grapes,  such  as  the  Ru- 
LANDER,  and  others,  contain  a  large  proportion  of  alcohol,  and 
are  similar  to  Spanish  wines  in  tlieir  flavor,  but  they  possess  no 
houquel. 

The  grapes  grown  at  the  Cape  from  Riesslings,  transplanted 
from  the  Rhine,  produce  an  excellent  wine,  which  does  not,  how- 
ever,  possess  the  aroma  peculiar  to  the  Rhenish  wine. 

It  is  evident,  from  these  facts,  that  the  acid  of  wines,  and  their 
characteristic  perfumes,  have  some  connexion,  for  they  are  al- 
ways found  together ;  and  it  can  scarcely  be  doubted  that  the 
presence  of  the  former  exercises  a  certain  influence  on  the  for- 
mation of  the  latter.  This  influence  is  very  plainly  observed  in 
the  fernientation  of  liquids  destitute  of  tartaric  acid,  and  particu- 
larly  of  those  which  are  nearly  neutral  or  alkaline,  such  as  the 
mash*  of  potatoes  or  corn. 

The  brandy  obtained  from  corn  and  potatoes  contains  an 
ethereal  oil  of  a  similar  composition  in  both,  to  which  these  li- 
quors owe  their  peculiar  smell.  This  oil  is  generated  during  the 
fermentation  of  the  mash;  it  exists  ready  formed  in   the   fer- 


*  Mash  is  the  mixture  of  malt,  potatoes,  and  water,  in  the  mash  tun,  a 
large  vessel  in  which  it  is  infused. 


ODORIFEROUS  PRODUCTS.  315 

mented  liquids,  and  distils  over  with  alcohol  when  a  gentle  heai 
is  applied. 

It  is  observed  that  a  greater  quantity  of  alcohol  is  obtained 
when  the  mash  is  made  quite  neutral  by  ashes  or  by  carbonate 
of  lime,  and  that  the  proportion  of  oil  in  the  brandy  also  is  in- 
creased. 

Now,  it  is  known  that  brandy  made  from  potatoe  starch,  which 
has  been  converted  into  sugar  by  dilute  sulphuric  acid,  is  com- 
pletely free  from  the  potatoe  oil,  so  that  this  substance  must  be 
generated  in  consequence  of  a  change  suffered  by  the  cellular 
tissue  of  the  potatoes  during  their  fermentation. 

Rxpei'ience  has  shown  that  the  simultaneous  fermentation  or 
putrefaction  of  the  cellular  tissue,  by  which  this  oil  is  gene- 
rated, may  be  completely  prevented  in  the  fabrication  of  brandy 
from  corn. 

The  same  malt,  which  in  the  preparation  of  brandy  yields  a 
fluid  containiag  the  oil  ol"  which  we  are  speaking,  affords,  in  the 
formation  of  beer,  a  spirituous  liquor  in  which  no  trace  of  that  oil 
can  be.  detected.  The  principal  difference  in  the  preparation  of 
the  two  liquids  is,  that  in  the  fermentation  of  wc^,  an  aromatic 
substance  (hops)  is  added,  and  it  is  certain  that  its  presence 
modifies  the  transformations  which  take  place.  Now,  it  is  known 
that  the  volatile  oil  of  mustard,  and  the  empyreumatic  oils,  arrest 
campletely  the  action  of  yeast ;  and  although  the  oil  of  hops  does 
not  possess  this  property,  still  it  diminishes,  in  a  great  degree,  the 
influence  of  decomposing  azotized  bodies  upon  the  conversion  of 
alcohol  into  acetic  acid.  There  is,  therefore,  reason  to  believe 
that  some  aromatic  substances,  when  added  to  fermenting  mix- 
tures, are  capable  of  producing  very  various  modifications  in  the 
nature  of  the  products  generated. 

Whatever  opinion,  however,  may  be  held  regarding  the  origin 
of  the  volatile  odoriferous  substances  obtained  in  the  fermenta- 
tion of  wine,  it  is  quite  certain   that  the  characteristic  smell  of 


*  In  the  manufactory  of  M.  Dubrunfaut,  so  considerable  a  quantity  of  thi» 
oil  is  obtained  under  certain  circumstances  from  brandy  made  from  potatoes 
that  it  iQ'ght  be  employed  for  the  purpose  of  illuminating  his  whole  manu  - 
facton'. 


316  VINOUS  FERMENTATION. 

wine  is  owing  to  an  ether  of  an  organic  acid,  resembling  one  of 
the  fatty  acids  (oenanthic  ether). 

It  is  only  in  liquids  containing  other  very  soluble  acids,  that 
the  fatty  acids  and  cenanthic  acid  are  capable  of  entering  into 
combination  with  the  ether  of  alcohol,  and  of  tlius  producing 
compounds  of  a  peculiar  smell.  This  ether  is  found  in  all  wines 
containing  a  free  acid,  but  is  absent  from  those  in  which  no  acids 
are  present.  This  acid,  therefore,  is  the  means  by  which  the 
smell  is  produced  ;  since  without  its  presence  ounanthic  ether 
could  not  be  formed. 

The  greatest  part  of  the  oil  of  brandy  made  from  corn  con- 
sists of  a  fatty  acid  not  converted  into  ether ;  it  dissolves  oxide 
of  copper  and  metallic  oxides  in  general,  and  combine*  with  the 
alkalies. 

The  principal  constituent  of  this  oil  is  an  acid  identical  in 
composition  with  cenanthic  acid,  but  different  in  properties. 
(Mulder.)  It  is  formed  in  fermenting  liquids,  which,  if  they  be 
acid,  contain  only  acetic  acid,  a  body  which  has  no  influence  in 
causing  other  acids  to  form  ethers. 

The  oil  of  brandy  made  from  potatoes  is  the  hydrate  of  an 
organic  base  analogous  to  ether,  and  capable,  therefore,  of  enter- 
ing into  combination  with  acids.  It  is  formed  in  considerable 
quantity  in  fermenting  liquids  possessing  an  alkaline  reaction  ; 
under  circumstances,  consequently,  in  which  it  is  incapable  of 
combining  with  an  acid. 

The  products  of  the  fermentation  and  putrefaction  of  neutral 
vegetable  and  animal  matters  are  generally  accompanied  by 
substances  of  an  offensive  odor  ;  bui  the  most  remarkable  exam- 
ple of  the  generation  of  a  true  ethereal  oil  is  seen  in  the  fermen- 
tation of  the  Centaurium  minus,  a  plant  destitute  of  smell.  When 
it  is  exposed  in  water  to  a  slightly  elevated  temperature  it  fer- 
ments,  and  emits  an  agreeable  penetrating  odor.  By  the  distil, 
lation  of  the  liquid,  an  ethereal  oily  substance  of  great  voletility 
is  obtained,  which  excites  a  pricking  sensation  in  the  eyes,  and 
a  flow  of  tears  (Buchner). 

We  know  that  most  of  the  blossoms  and  vegetable  substances 
possessing  a  smell  owe  this  property  to  a  volatile  oil  existing  in 


THE  BAVARIAN  PROCESS.  3n 


them  ;  but  it  is  not  less  certain,  that  others  emit  a  smell  only 
when  they  undergo  change  or  decomposition. 

Arsenic  and  arsenious  acid  are  both  quite  inodorous.  It  is  only 
during  their  oxidation  tliat  they  emit  their  characteristic  odor  of 
garlic.  The  oil  of  the  berries  of  the  elder-tree,  many  kinds  of 
oil  of  turpentine,  and  oil  of  lemons,  possess  a  smell  only  during 
their  oxidation  or  decay.  The  same  is  the  case  with  many 
blossoms  ;  and  Geiger  has  shown,  that  the  smell  of  musk  i'^; 
owing  to  its  gradual  putrefaction  and  decay. 

It  is  also  probable,  that  the  peculiar  odorous  principle  of  many 
vegetable  substances  is  newly  formed  during  the  fermentation  of 
the  saccharine  juices  of  the  plants.  At  all  events,  it  is  a  fact, 
that  very  small  quantities  of  the  blossoms  of  the  violet,  elder, 
linden,  or  cowslip,  added  to  a  fermenting  liquid,  are  sufficient  to 
communix3ate  a  very  strong  taste  and  smell,  which  the  addition 
of  the  water  distilled  from  a  quantity  a  hundred  times  greater 
would  not  effect.  The  various  kinds  of  beer  manufactured  in 
Bavaria  are  distinguished  by  different  flavors,  which  are  given 
by  allowing  small  quantities  of  the  herbs  and  blossoms  of  particu- 
lar plants  to  ferment  along  with  the  wort.  On  the  Rhine,  also, 
an  artificial  houquet  is  often  given  to  wine  for  fraudulent  pur- 
poses, by  the  addition  of  several  species  of  the  sage  and  rue  to 
the  fermenting  liquor  ;  but  the  fictitious  perfume  thus  obtained 
differs  from  the  genuine  aroma,  by  its  inferior  durability,  and  by 
being  gradually  dissipated. 

The  juice  of  grapes  grown  in  different  climates  differs  not  only 
in  its  proportion  of  free  acid,  but  also  in  respect  of  the  quantity  of 
sugar  dissolved  in  it.  The  quantity  of  azotized  matter  in  the  juice 
seems  to  be  the  same  in  whatever  part  the  grapes  may  grow  ;  at 
least,  no  difference  has  been  observed  in  the  amount  of  yeast 
formed  during  fermentation  in  the  south  of  France,  ard  on  the 
Rhine. 

The  grapes  grown  in  hot  climates,  as  well  as  the  boiled  juice 
obtained  from  them,  are  proportionally  rich  in  sugar.  Hence, 
during  the  fermentation  of  the  juice  the  complete  decomposition 
of  its  azotized  matters,  and  their  separation  in  the  insoluble  state, 
are  effected  before  all  the  sugar  has  been  converted  into  alcohol  and 
carbonic  acid.     A  certain  quantity  of  the   sugar  consequently 


318  VINOUS  FERMENTATION. 


remains  mixed  with  the  wine  in  an  undecomposed  state,  the  con- 
dition  necessary  for  its  further  decomposition  being  absent. 

The  azotized  matters  in  the  juice  of  grapes  of  the  temperate 
zones,  on  the  contrary,  are  not  completely  separated  in  the 
insoluble  state,  when  the  entire  transformation  of  the  sugar  is 
effected.  The  wine  of  these  grapes,  therefore,  does  not  contain 
sugar,  but  variable  quantities  of  undecomposed  gluten  in  solu- 
tion. 

This  gluten  gives  the  wine  the  property  of  becoming  spon- 
taneously  converted  into  vinegar,  when  the  access  of  air  is  not 
prevented.  For  it  absorbs  oxygen  and  becomes  insoluble  ;  and 
its  oxidation  is  communicated  to  the  alcohol,  which  is  converted 
into  acetic  acid. 

By  allowing  the  wine  to  remain  at  rest  in  casks  with  a  very 
limited  access  of  air,  and  at  the  lowest  possible  temperature,  the 
oxidation  of  this  azotized  matter  is  effected  without  the  alcohol 
undergoing  the  same  change,  a  higher  temperature  being  neces- 
sary to  enable  alcohol  to  combine  with  oxygen.  As  long  as  the 
wine  in  the  stil ling-casks  deposits  yeast,  it  can  still  be  caused  to 
ferment  by  the  addition  of  sugar,  but  old  well-cleared  wine  has 
lost  this  property,  because  the  condition  necessary  for  fermenta- 
tion, namely,  a  substance  in  the  act  of  decomposition  or  putre- 
faction, is  no  longer  present  in  it. 

In  hotels  and  other  places  where  wine  containing  much  gluten 
is  drawn  gradually  from  at  cask,  and  a  proportional  quantity  of 
air  necessarily  introduced,  its  eremacausis,  that  is,  its  conversion 
into  acetic  acid,  is  prevented  by  the  addition  of  a  small  quantity 
of  sulphurous  acid.  This  acid,  by  entering  into  combination  with 
the  oxygen  of  the  air  contained  in  the  cask,  or  dissolved  in  the 
wine,  prevents  the  oxidation  of  the  organic  matter. 

The  various  kinds  of  beer  diff*er  from  one  another  in  the  same 
way  as  the  wines. 

English,  French,  and  most  of  the  German  beers,  are  converted 
into  vinegar  when  exposed  to  the  action  of  air.  But  this  pro- 
perty is  not  possessed  by  Bavarian  beer,  which  may  be  kept  in 
vessels  only  half-filled  without  acidifying  or  experiencing  any 
change.  This  valuable  quality  is  obtained  for  it  by  a  peculiar 
management  of  the  fermentation  of  the  wort.     The  perfection  of 


THE  BAVARI  vN  PROCESS.  31B 

experimental  knowledge  has  here  led  to  the  solution  of  one  of  the 
most  beautiful  problems  of  the  theory  of  fermentation. 

Wort  is  proportionally  richer  in  gluten  than  in  sugar,  so  that, 
during  its  fermentation  in  the  common  way,  a  great  c/iantity  of 
yeast  is  formed  as  a  thick  scum.  The  carbonic  acid  evolved 
during  the  process  attaclies  itself  to  the  particles  of  the  yeast, 
by  which  they  become  specifically  lighter  than  the  liquid 
in  which  they  are  formed,  and  rise  to  its  surface.  Gluten,  in  the 
act  of  oxidation,  comes  in  contact  with  the  particles  of  the  decom- 
posing sugar  in  the  interior  of  the  liquid.  The  carbonic  acid 
from  the  sugar  and  insoluble  ferment  from  the  gluten  are  dis- 
engaged simultaneously,  and  cohere  together. 

A  great  quantity  of  gluten  remains  dissolved  in  the  fermented 
liquid,  even  after  the  transformation  of  the  sugar  is  completed, 
and  tins  gluten  causes  the  conversion  of  the  alcohol  into  acetic 
acid,  on  account  of  its  strong  disposition  to  attract  oxygen,  and  to 
undergo  decay.  Now,  it  is  plain,  that  with  its  separation,  and 
that  of  all  substances  capable  of  attracting  oxygen,  the  beer 
would-  lose  the  property  of  becoming  acid.  This  end  is  com- 
pletely attained  in  the  process  of  fermentation  adopted  in 
Bavaria. 

The  wort,  after  having  been  treated  with  hops  in  the  usual 
manner,  is  thrown  into  very  wide  flat  vessels,  in  which  a  large 
surface  of  the  liquid  is  exposed  to  the  air.  The  fermentation  is 
then  allowed  to  proceed,  while  the  temperature  of  the  chambers 
in  which  the  vessels  are  placed  is  never  allowed  to  rise  above 
from  450  to  50°  F.  The  fermentation  lasts  from  three  to  six 
weeks,  and  the  carbonic  acid  evolved  during  its  continuance  is 
not  in  large  bubbles  wliich  burst  upon  the  surface  of  the  liquid, 
but  in  small  bubbles  like  those  which  escape  from  an  acidulous 
mineral  water,  or  from  a  liquid  saturated  by  high  pressure.  The 
surface  of  the  wort  is  scarcely  covered  with  a  scum,  and  all  the 
yeast  is  deposited  on  the  bottom  of  the  vessel,  in  the  form  of  a 
fine  viscous  slime. 

In  order  to  obtain  a  clear  conception  of  the  great  difference 
Detwecn  the  two  kinds  of  fermentation,  it  may  perhaps  be 
sufficif  Tit  to  recall  to  mind  the  fact,  that  the  transformation  of 
gluten  or  of  other  azotized  matters  is  a   process  consisting  of 


320  FERMENIAI'ION   OF  BEER 


several  stages.  The  first  stage  is  the  conversion  of  the  gluten 
into  insoluble  ferment  in  the  interior  of  the  liquid,  and  as  the 
transformation  of  the  sugar  goes  on  at  the  same  time,  carbonic 
acid  and  yeast  are  simultaneously  disengaged.  It  is  known  with 
certainty,  that  this  formation  of  yeast  depends  upon  oxygen 
being  appropriated  by  the  gluten  in  the  aci  of  decomposition  ; 
but  it  has  not  been  sufficiently  shown,  whether  this  oxygen  ia 
derived  from  the  water,  from  the  sugar,  or  irom  the  gluten 
itself;  whether  it  combines  directly  with  the  gluten,  or  merely 
with  its  hydrogen,  so  as  to  form  water.  For  the  purpose  of 
obtaining  a  definite  idea  of  the  process,  we  may  designate  the 
first  change  as  the  stage  of  oxidation.  Tiiis  oxidation  of  the 
gluten  then,  and  the  transposition  of  the  atoms  of  the  sugar  into 
alcohol  and  carbonic  acid,  are  necessarily  attendant  on  each 
other,  so  that  if  the  one  is  arrested  tiie  other  must  also  cease. 

Now,  the  yeast  which  rises  to  tlie  surface  of  the  liquid  is  not 
the  product  of  a  complete  de(  ojnposition,  but  is  oxidized  gluten 
still  capable  of  undergoing  a  new  transfojination  by  the  transpo- 
sition of  its  constituent  elements.  By  virtue  of  this  condition  it 
lias  the  power  to  excite  fermentation  in  a  solution  of  sugar  ;  and 
if  the  gluten  be  also  present,  the  decomposing  sugar  induces  its 
conversion  into  fresh  yeast,  so  that,  in  a  certain  sense,  the  yeast 
appears  to  reproduce  itself. 

Yeast  of  this  kind  is  oxidized  gluten  in  a  state  of  jruiref action j 
and  by  virtue  of  this  state  it  induces  a  similar  transformation  in 
the  elements  of  the  sugar. 

The  yeast  formed  during  the  fermentation  of  Bavarian  beer 
is  oxidized  gluten  in  a  state  of  decat/.  The  process  of  decompo- 
sition which  its  constituents  arr^  siiiiering,  gives  rise  to  a  very 
protracted  putrefaction  (  fer/iienfalmi)  in  the  sugar.  The  inten- 
sity of  the  action  is  diminisherl  in  so  great  a  degree,  that  the 
gluten  which  the  fluid  still  ]H)lds  in  solution  takes  no  part  in  it ; 
the  sugar  in  fermentation  does  not  excite  a  similar  state  in  the 
gluten. 

But  the  contact  of  the  already  decaying  and  precipitated 
gluten  or  yeast,  causes  the  eremacausis  of  the  gluten  dissolved  in 
the  wort  ;  oxygen  gas  is  absorbed  from  the  air,  and  all  the  gluter 
in  solution  is  deposited  as  yeast. 


THE  BAVARIAN  PROCESS.  821 

The  ordinary  frothy  yeast  may  be  removed  from  fermenting 
beer  by  filtration,  without  the  fermentation  being  thereby  arrest- 
ed ;  but  the  precipitated  yeast  of  Bavarian  beer  cannot  be 
removed  without  the  whole  process  of  its  fermentation  being  in- 
terrupted. The  beer  ceases  to  ferment  altogether,  or,  if  thft 
temperature  is  raised,  undergoes  the  ordinary  fermentation. 

The  precipitated  yeast  does  not  excite  ordinary  fermentation, 
and,  consequently,  is  quite  unfitted  for  the  purpose  of  baking ; 
but  the  common  frothy  yeast  can  cause  the  kind  of  fermentation 
by  which  the  former  kind  of  yeast  is  produced. 

When  common  yeast  is  added  to  wort  at  a  temperature  of 
between  40*^  and  50°  F.,  a  slow  tranquil  fermentation  takes 
place,  and  a  matter  is  deposited  on  the  bottom  of  the  vessel, 
which  may  be  employed  to  excite  new  fermentation  ;  and  when 
the  same  operation  is  repeated  several  times  in  succession,  the 
ordinary  fermentation  changes  into  that  process  by  which  only 
precipitated  yeast  is  formed.  The  yeast  now  deposited  has  lost 
the  property  of  exciting  ordinary  fermentation,  but  it  produces 
the  other  process  even  at  a  temperature  of  50°  F. 

In  wort  subjected  to  fermentation,  at  a  low  temperature,  with 
this  kind  of  yeast,  the  condition  necessary  for  the  transformation 
of  the  sugar  is  the  presence  of  that  yeast  ;  but  for  the  conversion 
of  gluten  into  ferment  by  a  process  of  oxidation,  something  more 
is  required. 

When  the  power  of  gluten  to  attract  oxygen  is  increased  by 
contact  with  precipitated  yeast  in  a  state  of  decay,  the  unre- 
strained access  of  ai)  is  the  only  other  condition  necessary  for  its 
own  conversion  into  the  same  state  of  decay,  that  is,  for  its  oxida- 
tion. We  have  already  seen  that  the  presence  of  free  oxygen 
and  of  gluten  are  conditions  which  determine  the  eremacausis  of 
alcohol  and  its  conversion  into  acetic  acid,  but  they  are  inca- 
pable of  exerting  this  influence  at  low  temperatures.  A  low 
temperature  retards  the  slow  combustion  of  alcohol,  while  the 
gluten  combines  spontaneously  with  the  oxygen  of  the  air,  just 
as  sulphurous  acid  does  when  dissolved  in  water.  Alcohol  un- 
dergoes no  such  change  at  low  temperatures,  but  during  the  oxi- 
dation of  the  gluten  in  contact  with  it,  is  placed  in  the  same 
condition  as  the  gluten  itself  when  sulphurous  acid  is  added  to 
15* 


522  FERMENTATION  OF  BEER. 

the  wine  in  which  it  is  contained.  The  oxygen  of  the  air 
unites  both  with  the  gluten  and  alcohol  of  wine  not  treated  with 
sulphurous  acid  ;  but  when  this  acid  is  present  it  combines  with 
neither  of  them,  being  altogether  absorbed  by  the  acid.  The 
same  thing  happens  in  the  peculiar  process  of  fermentation 
adopted  in  Bavaria.  The  oxygen  of  the  air  unites  only  with 
the  gluten  and  not  with  the  alcohol,  although  it  would  have 
combined  with  both  at  higher  temperatures,  so  as  to  form 
acetic  acid. 

Thus,  then,  this  remarkable  process  of  fermentation  with  the 
precipitation  of  a  mucous-like  ferment  consists  of  a  simultaneous 
putrefaction  and  decay  of  the  same  liquid.  The  sugar  is  in  the 
state  of  putrefaction,  and  the  gluten  in  that  of  decay. 

Appert's  method  of  preserving  food,  and  this  kind  of  fermenta- 
tion  of  beer,  depend  on  the  same  principle. 

In  the  fermentation  of  beer  after  this  manner,  all  the  sub- 
stances  capable  of  decay  are  separated  from  it  by  means  of  an 
unrestrained  access  of  air,  while  the  temperature  is  kept  suffi- 
ciently low  to  prevent  the  alcohol  from  combining  witli  oxygen. 
The  removal  of  these  substances  diminishes  the  tendency  of  the 
beer  to  become  acescent,  or,  in  other  words,  to  suffer  a  further 
transformation. 

In  Appert's  mode  of  preserving  food,  oxygen  is  allowed  to 
enter  into  combination  with  the  substance  of  the  food,  at  a  tem- 
perature at  which  decay,  but  neither  putrefaction  nor  fermenta- 
tion, can  take  place.  With  the  subsequent  exclusion  of  the 
oxygen  and  the  completion  of  the  decay,  every  cause  which 
could  effect  further  decomposition  of  the  food  is  removed.  The 
conditions  for  putrefaction  are  rendered  insufficient  in  both 
cases  ;  in  the  one,  by  the  removrJ  of  the  substances  susceptible 
of  decay ;  in  the  other,  by  the  e?:clusicn  of  the  oxygen  which 
would  effect  it. 

It  has  been  stated  to  be  uncertain  whether  gluten,  during  its 
conversion  into  common  yeast,  that  is,  into  the  insoluble  state  in 
which  i';  separates  from  fermenting  liquids,  really  combines 
directly  with  oxygen.  If  it  does  combine  with  oxygen,  then  the 
difference  between  gluten  and  ferment  would  be,  that  the  latter 
Would  contain  a  larger  proportion  of  oxygen.     Now  it  is  very 


THE  BAVARIAN  PROCESS. 


difficult  to  ascertain  this,  and  even  the  analysis  of  these  substances 
cannot  decide  the  question.  Let  us  consider,  for  example,  the 
relations  of  alloxan  and  alloxantin*  to  one  another.  Both  of 
these  bodies  contain  the  same  elements  as  gluten,  although  in 
different  proportions.  Now  they  are  known  to  be  convertible 
into  each  other  by  oxygen  being  absorbed  in  the  one  case,  and 
in  the  other  extracted.  Both  arc  composed  of  absolutely  the 
same  elements,  in  equal  proportions ;  with  the  single  exception, 
that  alloxantin  contains  1  equivalent  of  hydrogen  more  than 
alloxan. 

When  alloxantin  is  treated  with  chlorine  or  nitric  acid,  it  is 
converted  into  alloxan  ;  into  a  body,  therefore,  which  is  alloxan- 
tin minus  1  equivalent  of  hydrogen.  If,  on  the  other  hand,  a 
stream  of  sulphuretted  hydrogen  is  conducted  through  alloxan, 
sulphur  is  precipitated,  and  alloxantin  produced.  It  may  be  said 
that,  in  the  first  case,  hydrogen  is  abstracted  ;  in  the  other,  added. 
But  it  would  be  quite  as  simple  an  explanation,  if  we  considered 
them  as  oxides  of  the  same  radical ;  the  alloxan  being  regarded 
as  a  combination  of  a  body  composed  of  Cg  Ng  Hg  Og  with  2 
equivalents  of  water,  and  alloxantin  as  a  combination  of  3  atoms 
of  water  with  a  compound  consisting  of  Cg  Nj  Hg  O^.  The 
conversion  of  alloxan  into  alloxantin  would  in  this  case  result 
from  its  eight  atoms  of  oxygen  being  reduced  to  seven  ;  while 
alloxan  would  be  formed  out  of  alloxantin,  by  its  combining  with 
an  additional  atom  of  oxygen. 

Now,  oxides  are  known  which  combine  with  water,  and  pre- 
sent the  same  phenomena  as  alloxan  and  alloxantin.  But  com- 
pounds of  hydrogen  are  not  known  to  form  hydrates ;  and  custom, 
which  rejects  all  dissimilarity  until  the  claim  to  peculiarity  is 
quite  proved,  leads  us  to  prefer  an  opinion  for  which  there  is  no 
further  foundation  than  that  of  analogy.  The  woad  {Isatis  tine- 
toria)  and  several  species  of  the  Nerium  contair-  a  substance 
similar  in  many  respects  to  gluten  ;  this  is  depos.ted  as  indigo 
blue,  when  an  aqueous  infusion  of  the  dried  leaves  is  exposed  to 
the  action  of  the  air.  Now  it  is  very  doubtful  whether  the  blue 
insoluble  indigo  is  an  oxide  of  the  colorless  soluble  indigo,  or  the 

*  Compounds  obtained  by  the  action  of  nitric  acid  on  uric  acid. 


^24  PERMENTATION  OF  BEER. 


latter  a  combination  of  hydrogen  with  the  indigo  blue.  Dumaa 
has  found  the  same  elements  in  both,  except  that  the  soluble 
compound  contained  1  equivalent  of  liydrogen  more  than  the 
blue. 

In  the  same  manner  the  soluble  gluten  may  be  considered  a 
compound  of  hydrogen,  which  becomes  ferment  by  losing  a  cer- 
tain quantity  of  this  element  when  exposed  to  the  action  of  the 
oxygen  of  the  air  under  favorable  circumstances.  At  all  events, 
it  is  certain  that  oxygen  is  the  cause  of  ihe  insoluble  condition 
of  gluten  ;  for  yeast  is  not  deposited  on  keeping  wine,  or  during 
the  fermentation  of  Bavarian  boer,  unless  oxygen  lias  access  to 
the  fluid. 

Now,  whatever  be  the  form  in  which  the  oxygen  unites  with 
the  gluten — whether  it  combines  directly  with  it,  or  extracts  'a 
portion  of  its  hydrogen,  forming  water — the  products  formed  in 
the  interior  of  the  liquid,  in  consequence  of  the  conversion  of 
the  gluten  into  ferment,  will  still  be  the  same.  Let  us  suppose 
that  gluten  is  a  compound  jof  another  substance  witli  hydrogen, 
then  this  hydrogen  must  be  removed  during  the  ordinary  fermen- 
tation of  must  and  wort,  by  combining  with  oxygen,  exactly  as 
in  the  conversion  of  alcohol  into  aldehyde  by  ereniacausis. 

In  both  cases  the  atmosphere  is  excluded ;  the  oxygen  cannot, 
then,  be  derived  from  the  air,  neither  can  it  he  supplied  by  the 
elements  of  water,  for  it  is  impossible  to  suppose  that  the  oxygen 
will  separate  from  the  hydrogen  of  water,  for  the  purpose  of 
uniting  with  the  hydrogen  of  gluten,  in  order  again  to  form 
water.  The  oxygen  must,  therefore,  be  obtained  from  the  ele- 
ments of  sugar,  a  portion  of  which  substance  must,  in  oixler  to 
the  formation  of  ferment,  undergo  a  different  decomposition  fr  .m 
that  which  produces  alcohol.  Hence  a  certain  part  of  the  sugar 
will  not  be  converted  into  carbonic  a^  id  and  alcohol,  but  will 
yield  other  products  containing  less  oxygen  than  sugar  itself  con- 
tains. These  products,  as  has  already  been  mentioned,  are  the 
cause  of  the  great  difference  in  the  qualities  of  fermented  liquids, 
and  particularly  in  their  quantity  of  alcohol. 

Must  and  wort  do  not,  therefore,  in  ordinary  fermentation, 
yield  alcohol  in  proportion  to  the  quantity  of  sugar  which  they 
hbH  in  solution,  a  part  of  the  sugar  being  employed  in  the  coo- 


THE  BAVARIAN  PROCESS.  'm 


version  of  gluten  into  ferment,  and  not  in  the  formation  of  alcohol. 
But  in  the  fermentation  of  Bavarian  beer,  all  the  sugar  is  ex- 
pended in  the  production  of  alcohol  ;  and  this  is  especially  the 
case  Avhenever  the  transformation  of  the  sugar  is  not  accom- 
panied by  the  formation  of  yeast. 

It  is  quite  certain  that  in  the  distilleries  of  brandy  from  potatoes., 
where  no  yeast  is  formed,  or  only  a  quantity  corresponding  to  the 
malt  which  has  been  added,  the  proportion  of  alcohol  and  car- 
bonic acid  obtained  during  the  fermentation  of  the  mash  cor- 
responds exactly  to  that  of  the  carbon  contained  in  the  starch. 
It  is  also  known  that  the  volume  of  carbonic  acid  evolved  during 
the  fermentation  of  beet-roots  gives  no  exact  indication  of  the 
proportion  of  sugar  contained  in  them,  for  less  carbonic  acid  is 
obtained  than  the  same  quantity  of  pure  sugar  would  yield. 

Beer  obtained  by  the  mode  of  fermentation  adopted  in  Bavaria 
contains  more  alcohol,  and  possesses  more  intoxicating  properties, 
than  that  made  by  the  ordinary  method  of  fermentation,  when 
the  quantities  of  malt  used  are  the  same.  The  strong  taste  of 
the  former  beer  is  generally  ascribed  to  its  containing  carbonic 
acid  in  larger  quantity,  and  in  a  state  of  more  intimate  combina- 
tion ;  but  this  opinion  is  erroneous.  Both  kinds  of  beer  are,  at 
the  conclusion  of  the  fermentation,  completely  saturated  with 
carbonic  acid,  the  one  as  much  as  the  other.  Like  all  other 
liquids,  they  both  must  retain  such  a  portion  of  the  carbonic  acid 
evolved  as  corresponds  to  their  temperature  and  power  of  solu- 
tion, that  is,  to  their  volumes. 

The  temperature  of  the  fluid  during  fermentation  has  a  very 
important  influence  on  the  quantity  of  alcohol  generated.  It  has 
been  mentioned,  that  the  juice  of  beet-roots  allowed  to  ferment  at 
from  86°  to  95°  (30°  to  35°  C.)  does  not  yield  alcohol ;  and  that 
afterwards,  in  the  place  of  the  sugar,  mannite,  a  substance  inca- 
pable of  fermentation,  and  containing  less  oxygen  than  sugar,  is 
found,  together  with  lactic  acid  and  mucilage.  The  formation 
of  these  products  diminishes  in  proportion  as  the  temperature  is 
lower.  But  in  vegetable  juices,  containing  nitrogen,  it  is  impos- 
sible to  fix  a  limit,  where  the  transformation  of  the  sugar  is  un- 
disturbed by  a  different  process  of  decomposition. 

It  is  known  that  in  the  fermentation  of  Bavarian  beer  the 


326  FERMENTATION  OF  BEER. 

action  of  the  oxygen  of  the  air,  and  the  low  temperature,  cause 
complete  transformation  of  the  sugar  into  alcohol ;  the  cause 
which  would  prevent  that  result,  namely,  the  attraction  of  the 
gluten  for  oxygen,  by  combining  with  which  it  is  converted  into 
ferment,  being  exercised  on  oxygen  derived  from  without. 

The  quantity  of  matters  in  the  act  of  transformation  is  na- 
turally greatest  at  the  beginning  of  the  fermentation  of  must  and 
wort  ;  and  all  the  phenomena  which  accompany  the  process, 
such  as  evolution  of  gas,  and  heat,  are  most  distinct  at  that  time. 
These  signs  of  the  changes  proceeding  in  the  fluid  diminish 
when  the  greater  part  of  the  sugar  has  undergone  decomposition  ; 
but  they  must  cease  entirely  before  the  process  can  be  regarded 
as  completed. 

The  less  rapid  process  of  decomposition  which  succeeds  the 
violent  evolution  of  gas,  continues  in  wine  and  beer  until  the 
sugar  has  completely  disappeared  ;  and  hence  it  is  observed, 
that  the  specific  gravity  of  the  liquid  diminishes  during  many 
months.  This  slow  fermentation,  in  most  cases,  resembles  the 
fermentation  of  Bavarian  beer,  the  transformation  of  the  dissolved 
sugar  being  in  part  the  result  of  a  slow  and  continued  decomposi- 
tion of  the  precipitated  yeast  ;  but  a  complete  separation  of  the 
azotized  substances  dissolved  in  it  cannot  take  place  when  air  is 
excluded.* 

Neither  alcohol  alone,  nor  hops,  noi  indeed  both  together,  pre- 
serve beer  from  becoming  acid.  The  better  kinds  of  ale  and 
porter  in  England  are  protected  from  acidity,  but  at  the  loss  of 
the  interest  of  an  immense  capital.  They  are  placed  in  large 
closed  wooden  vessels,  the  surfaces  of  which  are  covered  with 
eand.     In  these  they  are  allowed  to  lie  for  several  years,  so  that 


*  The  great  influence  which  a  rational  management  of  fermentation  has 
npon  the  quality  of  beer,  is  well  known  in  several  of  the  German  states. 
In  the  grand-duchy  of  Hesse,  for  example,  a  considerable  premium  is 
oflered  for  the  preparation  of  beer  according  to  the  Bavarian  method ;  and 
the  premium  is  to  be  adjudged  to  any  one  who  can  prove  that  the  beer 
brewed  by  him  has  lain  for  six  months  in  the  store-vats  without  becoming 
acid.  Hundreds  of  casks  of  beer  became  changed  to  vinegar  before  an  em- 
piricalTcnowledge  of  those  conditions  was  obtained,  the  influence  of  which' 
is  rendered  intelligible  by  theory 


THE  BAVARIAN  PROCESS.  327 

they  are  treated  in  a  manner  exactly  similar  to  wine  during  its 
ripening. 

A  gentle  diffusion  of  air  takes  place  through  the  pores  of  the 
wood,  but  the  quantity  of  azotized  substances  being  very  great 
in  proportion  to  the  oxygen  which  enters,  they  consume  it,  and 
prevent  its  union  with  the  alcohol.  But  the  beer  treated  in  this 
way  does  not  keep  for  two  months  without  acidifying,  if  it  be 
placod  i,i  s^nialier  vessels,  to  which  free  access  of  the  air  is 
permitted. 


328  FERMENTATION  ASCRIBED  TO  THE 


CHAPTER  X. 

Fermentation  ascribed  to  the  Growth  of  Fungi  and  of  Infuooria. 

The  microscopical  examination  of  vegetable  and  animal  mat. 
ter,  in  the  act  of  fermentation  or  putrefaction,  has  lately  given 
rise  to  the  opinion,  that  these  actions  themselves,  and  the  changes 
suffered  by  the  bodies  subjected  to  them,  are  produced  in  conse- 
quence of  the  development  of  fungi,  or  of  microscopical  animals, 
the  germs  or  eggs  of  which  are  supposed  to  be  diffused  every- 
where, in  a  manner  inappreciable  to  our  senses  ;  they  are  sup- 
posed to  be  developed  when  they  meet  with  a  medium  fitted  to 
afford  them  nourishment. 

Several  philosophers  have  ascribed  to  this  circumstance  the 
fermentation  of  wort,  and  of  the  juice  of  the  grape.  They  assert, 
that  the  decomposition  of  sugar  into  alcohol  and  carbonic  acid  is 
effected  by  the  contact  of  particles  of  the  sugar  with  the  growing 
plants,  which  they  view  as  the  yeast,  or  ferment,  without  study- 
ing more  closely  the  final  causes  of  the  decomposition  of  the 
sugar.  It  has  been  supposed  that  this  view  is  opposed  to  the 
theory  detailed  in  the  preceding  pages,  which  described  contact 
as  the  cause  of  a  peculiar  activity  or  power. 

In  all  chemical  processes,  and  in  all  changes  effected  by 
chemical  affinity,  we  observe  that  contact  is  essential  for  the  ex- 
ercise of  the  acting  power.  Hence,  chemists  describe  affinity  as 
a  force  distinct  from  other  powers,  because  it  acts  only  in  imme- 
diate  contact,  or  at  inappreciable  distances.  Thus  contact  plays 
an  important  part  in  every  case  of  combination  or  decomposition, 
for  without  contact  these  changes  would  not  take  place.  In  this 
sense,  all  substances  effecting  combination  or  decomposition  are 
bodies  acting  by  contact. 

In  the  theory  of  fermentation  alluded  to,  it  was  not  asserted 
that  the  yeast  or  ferment  could  effect  the  decomposition  of  sugar 


GROWTH  OF  FUNGI  AND  OF  INFUSORIA.  329 


at  appreciable  distances.  In  this  respect,  therefore,  the  two 
theories  are  not  opposed  to  each  other.  They  deviate,  however, 
in  this,  that  the  one  theory  considers  yeast  as  a  body,  the  smallest 
particles  of  which  are  in  a  state  of  motion  and  transposition,  and 
that,  by  virtue  of  this  state,  the  particles  of  sugar  in  contact  with 
it  are  thrown  into  the  same  state  of  change,  while  the  other 
theory  asserts,  that  the  particles  of  yeast  are  little  fungi,  which 
are  developed  from  germs  or  seeds  falling  into  the  fermenting 
liquid  from  the  air;  and  that  in  this  they  grow  at  the  expense  of 
the  substances  containing  nitrogen,  which  are  thus  converted  into, 
and  separated  as,  fungi.  The  particles  of  sugar  in  contact  with 
the  fungi  are  supposed  to  be  converted  into  carbonic  acid  and 
alcohol,  which,  in  other  words,  signifies,  that  the  act  of  vegetation 
effects  a  disturbance  in  the  chemical  attractions  of  the  elements 
of  the  sugar,  in  consequence  of  which  they  arrange  themselves 
into  new  compounds. 

Gay-Lussac  showed  by  experiments  that  the  juice  of  grapes 
expressed  apart  from  air,  under  a  bell-jar  full  of  mercury,  did 
not  er.ter  into  putrefaction,  although  it  did  so  in  the  course  of  a 
few  hours  when  air  was  admitted.  The  same  chemist  also  showed, 
that  fermentation  immediately  commences  on  the  introduction  of 
oxygen  gas,  of  which  a  quantity  is  absorbed  equal  only  to  the 
j^th  part  of  the  volume  of  carbonic  acid  evolved  during  the 
fermentation.  It  scarcely  can  be  supposed,  that  the  germs  of 
fungi  exist  in  chlorate  of  potash  or  black  oxide  of  manganese,  out 
of  which  the  oxygen  was  obtained ;  and  hence  it  is  difficult 
to  ascribe  to  a  growing  vegetation  the  causes  of  the  decom- 
position. 

Gay-Lussac  further  showed,  that  the  juice  entered  into  fer- 
mentation on  being  connected  with  the  wires  of  a  galvanic  battery, 
under  circumstances,  therefore,  which  quite  excluded  the  intro- 
duction of  every  foreign  body.  Hence  the  view,  that  tiie  fer- 
mentation of  sugar  IS  effected  by  contact  with  growing  plants, 
must  presuppose  that  living  beings,  plants  for  example,  may  be 
formed  and  developed  without  germs  or  seeds- — a  circumstance 
in  direct  contradiction  to  all  observation  regarding  the  growth 
of  plants. 

It  is  certain  that  sponges  and  fungi,  growing  in  places  from 


330  FERMPLNTATION  ASCRIBED  TO  THE 

which  light  is  quite  excluded,  follow  laws  of  nutrition  different 
from  those  governing  green  plants  ;  and  it  cannot  be  doubted  that 
their  nourishment  is  derived  from  putrefying  bodies,  or  from  the 
products  of  their  putrefaction,  which  paSvS  directly  into  this  kind 
of  plants,  and  obtain  an  organized  form  by  the  vital  powers  re- 
siding within  them.  During  their  growth  they  constantly  emit 
carbonic  acid,  increasing  in  weight  at  the  same  time,  while  all 
other  plants,  under  similar  circumstances,  would  decrease  in 
weight.  Hence  it  is  possible,  and  indeed  probable,  that  fungi 
may  have  the  power  of  growing  in  fermenting  and  putrefying 
substances,  in  as  far  as  the  products  arising  from  the  putrefaction 
are  adapted  for  their  nourishment.  When  a  quantity  of  fungi  are 
exposed  to  the  temperature  of  boiling  water,  their  vitality,  and 
power  of  germinating  become  completely  destroyed.  If  they  be 
now  kept  at  a  proper  temperature,  an  evolution  of  gas  proceeds 
in  the  mass  thus  treated  ;  they  pass  over  into  putrefaction,  and, 
if  air  be  admitted,  into  decay  ;  and  at  last  nothing  remains  ex- 
cept their  inorganic  elements.  The  putrefiiction  in  this  case 
cannot  be  viev/ed  as  the  act  of  the  formation  of  organic  beings, 
but  as  the  act  of  the  passage  of  their  elements  into  inorganic 
compounds. 

Observations  of  another  kind — for  example,  that  flesh  and  other 
animal  bodies  may  be  kept  for  several  weeks  without  putrefying, 
if  placed  in  a  vessel  containing  air  previously  heated  to  redness- 
— have  gone  far  to  support  the  opinion  tliat  the  process  of  putre- 
faction is  effected  by  the  growth  of  organic  beings ;  but  all  such 
experiments  are  of  very  subordinate  value  in  support  of  these 
conclusions.  In  some  experiments  instituted  by  the  author,  for 
the  purpose  of  detecting  quinine  in  the  urine  of  a  patient  in  the 
habit  of  taking  this  medicine,  he  obtained  the  remarkable  result, 
that  this  urine  kept  for  several  weeks  without  passing  into  com- 
plete putrefaction,  although  the  urea  of  urine,  under  ordinary 
circumstances,  is  often  completely  converted  into  carbonate  of 
ammonia  in  the  space  of  six  or  eight  hours.  In  the  present  case, 
the  urine  effervesced  only  siightly  with  acids  after  fourteen  dayss. 
This  seemed  to  give  sufficient  foundation  for  the  opinion  that  the 
quinine  must  be  the  cause  of  this  delay  in  the  putrefaction.  But 
further  experiments  proved  tiiat  common  urine  introduced  when 


GROWTH  01'*  FUNGI  AND  OF  INFUSORIA.  331 


freshly  drawn  into  perfectly  pure  vessels  behaved  in  an  exactly 
similai  manner.  When  a  little  putrefying  urine  was  added  to 
the  fresh  urine,  the  putrefaction  of  the  latter  was  accelerated  in 
a  high  Jegree.  Wood,  in  wliich  urine  had  been  retained,  ex- 
erted this  action  in  a  very  decided  manner,  and  the  white,  or 
yellowish- white  deposit  from  putrefying  urine  (which  does  not 
possess  an  organized  form)  effects  the  conversion  of  urea  into 
carbonate  of  ammonia  in  ihc  course  of  a  few  hours. 

Fresh  flesh  remains  for  several  weeks  without  experiencing 
appreciable  change  in  a  perfectly  pure  glass  vessel,  whether  the 
latter  contains  common  air,  or  air  previously  heated  to  redness : 
but,  at  the  same  time,  it  absorbs  oxygen,  and  emits  carbonic  acid, 
and  passes  into  putrefaction,  if  the  necessary  quantity  of  water 
be  present,  the  proces^^  not  being  prevented  or  retarded  by  the  ig- 
nition of  the  air. 

It  cannot  be  supposed,  that  dung-flies,  living  upon  animal  ex- 
crements, are  the  cause  of  this  putrefaction  ;  neither  can  a  similar 
conclusion  be  drawn  in  the  case  of  mites  and  maggots  found  so 
abundantly  in  old  cheese. 

When  we  consider,  that  the  intermediate  products  formed  in 
the  passage  of  animal  and  vegetable  matters  into  inorganic  com- 
pounds possess  the  power  of  supporting  the  life  of  certain  ani- 
mals and  vegetables  low  in  the  scale  of  creation,  then  the  only 
mystery  is,  in  what  manner  the  germs  of  the  fungi,  or  the  eggs 
of  the  infusoria,  reach  the  place  fitted  for  tb.eir  development ;  for 
this  being  known,  there  is  no  difficulty  since  the  discoveries  of 
Ehrcnberg,  in  conceiving  this  extraordinary  increase.  Nov/,  as 
it  is  observed  that  the  infusoria  increase  in  size  only  to  a  certain 
point,  it  must  hence  be  concluded  that  their  nourishment,  even  if 
only  from  the  point  at  which  they  are  to  grow,  passes  out  of  their 
bodies  in  the  form  of  excrements,  precisely  as  in  the  higher  order 
of  ar.inihis.  As  in  the  case  with  all  other  excrements,  these 
nmst  possess,  in  an  eminent  degree,  the  property  of  passing  into 
decay  or  putrefaction  ;  and  this  condition  must  at  all  events  be 
induced  by  contact  with  the  original  putrefying  body.  Hence 
the  increase  in  numbers  of  the  infusoria  must  induce  and  acce- 
lerate the  process  of  putrefaction  in  the  putrefying  body  itself. 
The  ultimate  products  of  decay  <ind  putrefaction  are  carbonic 


332  FERMENTATION  ASCRIBED  TO  THE 


acid,  ammonia,  and  water.  In  order  to  comprehend  the  chemical 
process  by  which  this  conversion  is  effected,  it  is  of  rnucli  interest 
to  become  acquainted  with  the  intermediate  compounds  formed 
by  the  elements.  But  in  regard  to  the  process  itself,  it  is,  che- 
mically speaking,  quite  indifferent  whether  the  first,  second,  or 
third  product,  before  they  assume  the  final  state,  be  in  the  form 
of  fungi,  or  of  living  animals  (infusoria).  These  plants  and  ani- 
mals are  not  the  causes  of  the  conversion,  for  they  suffer  after 
death  the  same  changes  which  finally  occasion  their  complete 
disappearance. 

The  enormous  layers  of  microscopic  animals  in  the  chalk  (the 
siliceous  infusoria)  do  not  contain  any  organic  matter.  The  lime 
of  their  shells,  and  the  silica  of  their  bony  coverings,  were  ob- 
tained from  the  water  in  which  they  were  developed.  Jf  this 
water  had  been  deficient  in  lime,  or  in  silica,  these  animals  could 
not  have  been  produced  ;  and  if  they  had  not  found  nourishment 
in  the  products  of  the  putrefaction  of  former  species  (the  remains 
of  vvhich  are  found  in  the  jnusc/ie/kalk),  they  would  not  have  been 
developed  ;  and  without  the  co-operation  of  both  these  causes, 
they  could  not  have  formed  such  extensive  masses  and  layers  as 
they  actually  do. 

But  these  animals  are  not  the  causes  of  the  formation  of  the 
chalk,  or  of  the  layers  of  flint,  and  as  little  are  they  the  cause  of 
the  decay  and  putrefaction  of  those  substances,  which  yielded  to 
them  their  organic  constituents.  Without  these  animals  there 
might  not  have  been  chalk,  but  there  would  liave  been  marble,  or 
another  limestone  ;  and  the  silica  would  have  been  deposited  as 
siliceous  schist,  or  as  quartz,  after  the  evaporation  of  the  water. 
Hence  it  is  only  the  form  which  is  given  to  the  layers  by  organic 
life  ;  but  the  substance  of  these  strata  (chalk)  is  chemically  in  no 
respect  different  from  crystallized  calcareous  spar:  in  fact,  the 
same  explanation  of  their  origin  might  be  made  as  that  adopted  in 
the  case  of  the  older  limestone  formations. 

The  conversion  of  the  constituents  of  an  elephant  into  aerial 
compounds  is  the  same  process,  and  is  effected  by  the  same  causes 
as  those  occasioning  the  destruction  of  the  carcase  of  the  micro- 
Bcopical  animals,  which  themselves  obtanied  their  elements  from 


GROWTH  OF  FUNGI  AND  OF  INFUSORIA.  333 


extinct  species  of  other  animals.  The  final  products  are  identical 
in  both  cases. 

There  have  been  very  wonderful  and  incomprehensible  ob- 
servations ma(^e  on  the  behavior  and  functions  of  certain  mi- 
croscopic animals.  From  these  observations,  there  seem  to  follow 
conclusions  regarding  the  nutrition  and  growth  of  these  creatures, 
quite  at  variance  with  all  that  we  know  of  the  process  of  nutrition 
of  the  higher  classes  of  animals. 

In  a  treatise  on  the  composition  of  the  salt-springs  in  Hesse- 
Cassel,  Pfannkuch  mentions  a  singular  phenomenon,  that  the 
slimy  mass  which  deposits  in  the  tub  set  to  receive  the  brine  per- 
colating through  the  wells  of  the  graduating-house,  contains  a  gas 
which  is  found  to  be  pure  oxygen  gas.  The  fresh  brine  obtained 
directly  from  the  draw-well  is  quite  clear,  and  contains  5  per 
cent,  of  salt  with  gypsum  and  sulphuretted  hydrogen  in  such  con- 
siderable quantity  that  it  might  be  used  as  a  sulphureous  water. 
During  the  summer  months,  a  slimy  transparent  mass  forms  in 
this  brine,  covering  the  bottom  of  the  vessel  containing  it  to  the 
depth  of  one  to  two  inches.  This  matter  is  everywhere  filled 
with  bubbles  of  gas,  of  a  considerable  size,  often  two  or  three 
inches  broad  ;  these  rise  to  the  surface,  when  the  membrane  in- 
closing them  is  torn  with  a  stick.  The  quantity  of  these  gas- 
bubbles  is  so  great,  that  it  would  be  easy  to  fill  hundreds  of 
bottles  with  them  in  a  short  time.  They  are  so  rich  in  oxygen 
gas,  that  a  glowing  match  of  wood  introduced  into  the  collected 
ga.s,  bursts  into  flame,  and  continues  to  burn  with  brilliancy.  On 
being  analysed,  this  gas  is  found  to  consist  of  51  per  cent,  of 
oxygen,  and  49  per  cent,  of  nitrogen ;  but  there  can  be  little 
doubt  that  the  gas  originally  consisted  of  pure  oxygen,  which  be- 
came mixed  with  the  nitrogen  of  air  by  virtue  of  diffusion,  just  as 
it  does  when  confined  in  an  animal  membrane.  In  fact,  it  is 
found,  that  when  the  water  in  the  tubs  is  very  low,  the  bubbles 
existing  in  the  deposit  appear  to  be  pure  air,  owing  to  the  celerity 
with  which  the  diffusion  has  taken  place  (Wohler). 

Wohler  has  subjected  to  microscopical  examination  the  slimy 
membranous  deposit,  and  has  shown  that  it  consists  almost  en- 
tirely of  living  and  moving  infusoria,  principally  species  of  Na- 
vicula  and  Gallionella,  such  as  occur  in  the  paper-like  formations 


134  FERMENTATION  ASCRIBED  TO  THE 


of  Freiberg,  and  in  the  siliceous  fossil  strata  of  Franzensbad. 
The  whole  deposit  possesses  a  slight  greenish  color,  and  is  in. 
tersected  with  very  fine  colorless  fibres  of  confervse.  After 
washing  and  drying  the  deposit,  a  residue  like  paper  isoMained  : 
and  this,  on  being  heated,  gives  distinct  indications  of  ammonia, 
showing  that  it  contains  nitrogen.  It  yields  also  a  mass  resem- 
bling paper,  which,  on  incineration,  being  treated  with  muriatic 
acid,  leaves  behind  siliceous  skeletons,  which  preserve  the  shape 
of  the  animal  so  completely,  that  it  appears  as  if  the  original  de- 
posit itself  were  submitted  to  examination  (Wohler). 

These  observations  are  of  remarkable  interest,  for,  as  Wohler 
asks — Whence  comes  the  oxygen  gas — from  the  confervse  or  from 
the  infusoria  ?  The  quantity  of  oxygen  being  so  large,  and  the 
infusoria  being  in  great  preponderance,  would  lead  to  the  con- 
clusion that  the  former  must  be  derived  from  these  ;  and  yet  this 
is  opposed  to  all  analogy.  The  water  comes  out  of  a  depth  of 
500  feet;  ar^d  its  sulphuretted  hydrogen  shows  that  it  comes  out 
of  a  layer  of  rocks  containing  putrefying  animal  matter,  which, 
acting  upon  the  sulphates,  produces  sulphuretted  hydrogen;  and 
in  this  water  is  formed,  with  the  aid  of  solar  light,  a  source  of 
oxygen  gas,  to  all  appearances  more  abundant  than  we  see  in  the 
case  of  green  plants.  Sir  B.  Thompson  (better  known  as  Count 
Rumford)  published  some  experiments  56  years  since,  which  are 
of  such  a  remarkable  nature,  that  we  give  them  in  the  author's 
own  words.  Thompson  found  that  silk,  cotton,  sheep's  wool, 
eider-down,  and  other  organic  substances,  evolve  oxygen  gas, 
when  they  are  freed  from  air  by  washing,  and  then  exposed  to 
sun-light  in  a  glass  globe  perfectly  filled  with  water.  After  two 
or  three  days,  the  water  assumed  a  greenish  hue,  and  from  that 
moment  the  evolution  of  gas  commenced. 

"  One  hundred  and  twenty  grains  of  cotton,  in  a  bell  jar, 
along  with  296  cubic  inches  of  spring  water,  gave  out,  during 
the  first  four  days,  2j  C.  I.  of  gas,  containing  hardly  any  oxy- 
gen. It  was  not  till  the  sixth  day,  when  the  sun  was  very  pow- 
erful,  that  the  water  suddenly  became  green,  and  gave  out  dur- 
ing the  next  six  days,  44^  C.  I.  of  oxygen  nearly  pure.  On 
examining  the  water  under  the  microscope,  it  was  found  to  con- 
lain  a  multitude  of  very  minute,  nearly  spherical  animalcules. 


GROWTH  OF  FUNGI  AND  OF  INFUSORIA.  S35 

Wherever  the  water  was  green,  these  animalcules  were  found, 
insomuch  that  the  green  color  seemed  to  be  caused  by  them.'' 
After  describing  hi^  numerous  experiments.  Count  Rumford 
adds — 

*'  The  phenomena  now  described  may,  perhaps,  admit  of  ex- 
planation, if  we  assume  that  the  air  produced  in  the  water  in  the 
different  experiments  was  derived  from  the  green  matter;  and 
that  the  leaves,  silk,  cotton,  &;c.,  only  facilitate  its  disengagement 
by  furnishing  a  surface  adapted  to  the  collection  and  escape  of 
the  gas-bubbles. 

"  These  phenomena  may  also  be  explained  by  an  assumption 
favorable  to  the  hypothesis  of  Priestley,  namely,  that  the  green 
matter  consists  of  plants,  which,  adhering  to  the  surface  of  the 
bodies  placed  in  the  water,  there  vegetate,  and  in  consequence 
give  rise  to  the  gas. 

"  I  would  willingly  adopt  this  opinion,  were  it  not  that  a  most 
careful  and  attentive  examination  of  the  green  water  by  means 
of  an  excellent  microscope,  at  the  period  when  the  oxygen  was 
most  abundantly  disengaged,  has  convinced  me,  that  at  this  pe- 
riod nothing  to  which  the  name  of  vegetable  can  be  given  is  pre- 
sent. The  coloring  matter  of  the  water  is  of  an  animal  nature, 
and  is  nothing  else  than  the  accumulation  of  an  infinite  number 
of  little  moving  animals." — Philosophical  Transactions  of  the 
Royal  Society,  Vol.  Ixxvii.,  1787. 

In  a  very  interesting  memoir,  by  Messrs.  August  and  Morren 
(Transactions  of  the  Academy  of  Brussels,  1841),  it  is  shown 
that  water  with  organic  substances  evolves  "  a  gas"  which  con- 
tains 61  per  cent,  of  oxygen  ;  and  they  conclude  their  trea- 
tise  in  the  following  words : — "  It  follows  from  the  preceding  re- 
rjiarks,  that  the  phenomenon  of  the  evolution  of  oxygen  gas  is 
due  to  the  Chlmnidomonas  piihisculus  (Ehrenhcrg),  and  to  several 
other  green  animals  still  lower  in  the  scale." 

The  author  took  the  opportunity  of  convincing  himself  of  the 
accuracy  of  this  long-observed  fact,  by  means  of  some  water  out 
of  a  water-trough  in  his  garden,  the  water  being  colored  strongly 
green  by  different  kinds  of  infusoria.  This  water  was  freed  by 
means  of  a  sieve  from  all  particles  of  vegetable  matter,  and  be- 
ing placed  in  a  jar,  inverted  in  a  porcelain  vessel  containing  the 


33(J  FERMENTATION  ASCRIBED  TO  THE 

same  water,  was  exposed  for  several  weeks  to  the  action  of  solar 
light.  During  this  time,  a  continued  accumulation  of  gas  took 
place  in  the  upper  part  of  this  jar  ;  after  fourteen  days  ^  of  the 
water  in  the  jar  had  been  pressed  out  of  it,  and  the  gas,  which 
had  taken  its  place,  ignited  a  glowing  match  of  wood,  and  in 
all  respects  behaved  like  pure  oxygen  gas.  It  must  be  here  ex- 
pressly stated,  that  the  water,  before  being  exposed  to  the  action 
of  solar  light,  was  examined  by  one  of  Ploessl's  best  micro- 
scopes, witiiout  the  detection  of  confervae  or  of  any  kind  of  ve- 
getable matter.* 

Without  venturing  upon  any  opinion  on  the  mode  of  nutrition 
of  these  animals,  it  is  quite  certain  that  water  containing  living 
infusoria  becomes  a  source  of  oxygen  gas  when  exposed  to'  the 
action  of  light.  It  is  also  certain,  that  as  soon  as  these  animals 
can  be  detected  in  the  water,  the  latter  ceases  to  act  injuriously 
to  plants  or  animals  ;  for  it  is  impossible  to  assume  that  pure 
oxygen  gas  can  be  evolved  from  water  containing  any  decaying 
or  putrefying  matters,  for  these  possess  the  property  of  combin- 
ing with  oxygen.  Now  it  is  obvious,  if  we  add  to  such  water 
any  animal  or  vegetable  matter  in  a  state  of  decay,  that  this, 
being  in  contact  with  oxygen,  will  resolve  itself  into  the  ultimate 
products  of  oxidation  in  a  much  shorter  time  than  if  infusoria 
were  not  present. 

Thus  we  recognise  in  these  animals,  or  perhaps  on'ly  in  certain 
classes  of  them,  by  means  of  the  oxygen  which  in  some  way,  as 
yet  incomprehensible,  accompanies  their  appearance,  a  most  wise 
and  wonderful  provision  for  removing  from  water  the  substance^ 
hurtful  to  the  higher  classes  of  animals;  and  for  substituting,  iu 
their  stead,  the  food  of  plants  (carbonic  acid),  and  the  oxygen 
gas  essential  to  the  respiration  of  animals.  They  cannot  be 
viewed  as  the  causes  of  putrefaction,  or  of  the  generation  of  pro- 
ducts injurious  to  animal  and  vegetable  life  ;  but  they  make  their 
appearance  in  order  to  accelerate  the  conversion  of  putrefying 
organic  matter  into  its  ultimate  products. 

•  One  hundred  cubic  inches  of  water  saturated  with  air  contained,  iu 
the  form  of  air,  according  to  the  experiments  of  Humboldt  and  Gsgrrl^^Uf- 
•ac,  not  above  V6  cubic  inches  of  oxygen  gas.  '  "^ 


GROW  m  OF  FUNGI  AND  OF  INFUSORIA.  337 


Many  fungi  grow  without  light,  and  in  their  growth  and  life 
are  characterized  by  all  tiie  phenomena  which  characterize  ani- 
mal life ;  they  destroy  air  by  absorbing  oxygen  and  evolving 
carbonic  acid,  and,  in  a  chemical  point  of  view,  behave  like  ani- 
mals without  motion.     (See  Appendix  to  Part  II.) 

In  opposition  to  this  class  of  beings,  which  can  scarcely  be 
designated  as  plants,  we  have  living  creatures  endowed  with 
motion,  and  with  the  organs  which  characterize  animals,  and 
yet  which  behave  in  the  light  like  green  plants ;  for  while 
they  increase  in  size  and  number,  they  furnish  sources  of  oxy- 
gen when  its  access,  in  the  form  of  air,  is  excluded  or  prevented. 

16 


138  DECAY  OF  WOODY  FIBRE. 


CHAPTER  XI. 

Decay  of  Woody  Fibre. 

The  conversion  of  woody  fibre  into  the  substances  termed  hu- 
mus and  mould  is,  on  account  of  its  influence  on  vegetation,  one 
of  the  most  remarkable  processes  of  decomposition  in  nature. 

Decay  is  not  less  important  in  another  point  of  view ;  for, 
by  means  of  its  influence  on  dead  vegetable  matter,  the  oxy- 
gen retained  by  plapts  dLring  life  is  again  restored  to  the  atmo- 
sphere. 

The  decomposition  of  woody  fibre  is  effected  in  three  forms, 
the  results  of  which  are  diflTerent,  so  that  it  is  necessary  to  con- 
sider each  separately. 

The  first  takes  place  when  it  is  in  the  moist  condition,  and 
subject  to  free  uninterrupted  access  of  air ;  the  second  occurs 
when  the  air  is  excluded  ;  and  the  third  when  the  wood  is  covered 
with  water,  and  in  contact  m  ith  putrefying  organic  matter. 

It  is  known  that  woody  fibre  may  be  kept  under  water,  or  in 
dry  air,  for  thousands  of  years,  without  suflTering  any  appreci- 
able change  ;  but  that  when  brought  into  contact  with  air,  in  the 
moist  condition,  it  converts  the  oxygen  surrounding  it  mto  the 
same  volume  of  carbonic  acid,  and  is  itself  gradually  changed 
into  a  yellowish-brown,  or  black  matter,  of  a  loose  texture.  Ac- 
cording to  the  experiments  of  De  Saussure,  240  parts  of  dry 
sawdust  of  oak-wood  convert  10  cubic  inches  of  oxygen  into  the 
same  quantity  of  carbonic  acid,  which  contains  3  parts,  by  weight, 
of  carbon ;  while  the  weight  of  the  sawdust  is  diminished  by  15 
parts.  Hence,  12  parts,  by  weight,  of  water,  are  at  the  same 
time  separated  from  the  elements  of  the  wood. 

Carbonic  acid,  water,  and  mould  or  humus,  are  therefore  the 
products  of  the  decomposition  of  wood.  We  have  assumed  that 
the  water  is  formed  by  the  combination  of  the  hydrogen  of  the 


DECAY  OF  WOODY  FIBRE. 


wood  with  the  oxygen  of  the  atmosphere,  and  that  during  the 
process  of  oxidation  carbon  and  oxygen  escape  from  the  wood 
of  carbonic  acid. 

It  has  already  been  mentioned,  that  pure  woody  fibre  con- 
tains carbon  and  the  elements  of  water.  Humus,  however,  is 
not  produced  by  the  decay  of  pure  woody  fibre,  but  by  that  of 
wood  which  contains  foreign  soluble  and  insoluble  organic 
substances,  besides  its  essential  constituents. 

The  relative  proportions  of  the  component  elements  are,  on  this 
account,  different  in  oak  wood  and  in  beech,  and  the  composition 
of  both  of  these  again  differs  from  woody  fibre,  which  is  the  same 
in  all  vegetables.  The  difference,  however,  is  so  trivial,  that  it 
may  be  altogether  neglected  in  the  consideration  of  the  questions 
which  will  now  be  brought  under  discussion ;  besides,  the  quan- 
tity of  the  foreign  substances  is  not  constant,  but  varies  according 
to  the  season  of  the  year. 

According  to  the  careful  analysis  of  Gay-Lussac  and  Thenard, 
100  parts  of  oak-wood,  dried  at  212*^  (100°  C),  from  which  all 
soluble  substances  had  been  extracted  by  means  of  water  and 
alcohol,  contained  52-53  parts  of  carbon,  and  47-47  parts  of  hy- 
drogen and  oxygen,  in  the  same  proportion  as  they  are  contained 
in  water.  ^'ti^^i'A 

Now  it  has  been  mentioned  that  moist  wood  acts  in  oxygen  gas 
exactly  as  if  its  carbon  combined  directly  with  oxygen,  and  that 
the  products  of  this  action  are  carbonic  acid  and  humus. 

If  the  action  of  the  oxygen  were  confined  to  the  carbon  of  the 
wood,  and  if  nothing  but  carbon  were  removed  from  it,  the  re- 
maining elements  would  necessarily  be  found  in  the  humus,  un- 
changed, except  in  the  particular  of  being  combined  with  less 
carbon.  The  final  result  of  the  action  would  therefore  be  a  com- 
plete disappearance  of  the  carbon,  whilst  nothing  but  the  ele- 
ments of  water  would  remain. 

But  when  decaying  wood  is  subjected  to  examination  in  dif- 
ferent stages  of  decay,  the  remarkable  result  is  obtained,  that 
the  proportion  of  carbon  in  the  different  products  augments. 
Consequently,  if  we  did  not  take  into  consideration  the  evolution 
of  carbonic  acid  under  the  influence  of  the  air,  the  conversion 


340  DECAY  OF  WOODY  FIBRE. 


of  wood  into  humus  might  be  viewed  as  a  removal  of  the  elementa 
of  water  from  the  carbon. 

The  analysis  of  mouldered  oak-wood,  taken  from  the  interioE 
of  the  trunk  of  an  oak,  and  possessing  a  chocolate-brown  color 
and  the  structure  of  wood,  showed  that  100  parts  of  it  contained 
53-36  parts  of  carbon  and  46*44  parts  of  hydrogen  and  oxygen 
in  the  same  relative  proportions  as  in  water.  From  an  examina- 
tion of  mouldered  wood  of  a  light-brown  color,  easily  reducible 
to  a  fine  powder,  and  taken  from  another  oak,  it  appeared  that  it 
contained  56-211  carbon  and  43-789  water. 

These  indisputable  facts  point  out  the  similarity  of  the  decay 
of  wood,  witli  all  other  instances  of  the  slow  combustion  or  oxi- 
dation of  bodies  containing  a  large  quantity  of  hydrogen.  Viewed 
as  a  kind  of  combustion,  it  would  indeed  be  a  very  extraordinary 
process,  if  the  carbon  combined  directly  with  the  oxygen  ;  for 
it  would  be  a  combustion  in  which  the  carbon  of  the  burning 
body  augmented  constantly,  instead  of  diminishing.  Hence  it  is 
evident  that  it  is  the  hydrogen  which  is  oxidized  at  the  expense 
of  the  oxygen  of  the  air  ;  while  the  carbonic  acid  is  formed  from 
the  elements  of  the  wood.  Carbon  never  combines  at  common 
temperatures  with  oxygen,  so  as  to  form  carbonic  acid. 

In  whatever  stage  of  decay  wood  may  be,  its  elements  must 
always  be  capable  of  being  i-epresented  by  their  equivalent 
numbers. 

The  following  formulae  illustrate  this  fact  with  great  precision : 

^3C    ^2  2    ^2  2 — oak  wood,  according  to  Gay-Lussac  and  Th^nard.* 
Cjg  ^2  0  ^2  0 — hurous  from  oak-wood  (Meyer). t 
^34   "is    0,,-  »  „  (Dr.  Will.)? 

It  is  evident  from  these  numbers,  that  for  every  two  equiva- 
lents of  hydrogen  oxidized,  two  atoms  of  oxygen  and  one  of  car- 
bon are  set  free. 

Under  ordinary  circumstances,  woody  fibre  requires  a  very^ 
long  time  for  its  decay;  but  this  process  is  of  course  nmuch 

•  The  calculation  from  this  formula  gives  52"5  carbon,  and  47*5  water 
t  The  calculation  gives  54  carbon,  and  46  water. 
X  The  calculation  gives  56  carbon,  and  44  water. 


DECAY  OF  WOODY  FIBRE.  M' 


accelerated  by  an  elevated  temperature  and  free  unrestrainea 
access  of  air.  The  decay,  on  the  contrary,  is  much  retarded  by 
the  absence  of  moisture,  and  by  the  wood  being  surrounded  with 
an  atmosphere  of  carbonic  acid,  which  prevents  the  access  of  air 
to  [he  decaying  matters. 

Sulphurous  acid,  and  all  antiseptic  substances,  arrest  the 
decay  of  woody  fibre.  It  is  well  known  that  corrosive  subli- 
mate is  employed  for  the  purpose  of  protecting  the  timber  of 
ships  from  decay  ;  it  is  a  substance  which  completely  deprives 
vegetable  or  animal  matters,  the  most  prone  to  decomposition,  of 
their  property  of  entering  into  fermentation,  putrefaction,  or 
decay. 

But  the  decay  of  woody  fibre  is  very  much  accelerated  by 
contact  with  alkalies  or  alkaline  earths ;  for  these  enable  sub- 
stances to  absorb  oxygen,  although  they  do  not  possess  this 
power  themselves :  alcohol,  gallic  acid,  tannin,  the  vegetable 
coloring  matters,  and  several  other  substances,  are  thus  affected 
by  them.  Acids  produce  quite  an  opposite  effect ;  they  greatly 
retard  decay. 

Heavy  soils,  consisting  of  loam,  retain  longest  the  most  im- 
portant condition  for  the  decay  of  the  vegetable  matter  contained 
in  them,  viz.  water ;  but  their  impermeable  nature  prevents 
contact  with  the  air. 

In  moist  sandy  soils,  particularly  such  as  are  composed  of  a 
mixture  of  sand  and  carbonate  of  lime,  decay  proceeds  very 
quickly,  it  being  aided  by  the  presence  of  the  slightly  alkaline 
lime. 

Now  let  us  consider  the  decay  of  woody  fibre  during  a  very 
long  period  of  time,  and  suppose  that  its  cause  is  the  gradual 
removal  of  the  hydrogen  in  the  form  of  water,  and  the  separation 
of  its  oxygen  in  that  of  carbonic  acid.  It  is  evident  that  if  we 
snbtract  from  the  formula  C,g  Hg,  O,,  the  22  equivalents  of 
oxygen,  with  11  equivalents  of  carbon,  and  22  equivalents  of 
hydrogen,  which  are  supposed  to  be  oxidized  by  the  oxygen  of 
the  air,  and  separated  in  the  form  of  water ;  then  from  1  atom  of 
oak-wood,  25  atoms  of  pure  carbon  will  remain  as  the  final  pro- 
duct of  the  decay.  In  other  words,  100  parts  of  oak,  containing 
52-5  parts  of  carbon,  will  leave  as  a  residue  36-5  parts  of  car- 


342  DECAY  OF  WOODY  FIBRE; 


Don,  which  must  remain  unchanged,  since  carbon  does  not  com- 
bine  with  oxygen  at  common  ten:  peratures. 

But  this  final  result  is  never  attained  in  the  decay  of  wood 
under  common  circumstances  ;  and  for  this  reason,  that  with  the 
increase  of  the  proportion  of  carbon  in  the  residual  humus,  as  in 
all  decompositions  of  this  kind,  its  attraction  for  the  hydrogen, 
which  still  remains  in  combination,  also  increases,  until  at 
length  the  affinity  of  oxygen  for  the  hydrogen  is  equalled  by  that 
of  the  carbon  for  the  same  element. 

In  proportion  as  the  decay  of  woody  fibre  advances,  its  pro- 
perty of  burning  with  flame,  or,  in  other  words,  of  developing 
carburetted  hydrogen  on  the  application  of  heat,  diminishes. 
Decayed  wood  burns  without  flame  ;  whence  no  other  conclij- 
sion  can  be  drawn,  than  that  the  hydrogen,  which  analysis 
shows  to  be  present,  is  not  contained  in  it  in  the  same  form  as 
m  wood. 

Decayed  oak  contains  more  carbon  than  fresh  wood,  but  its 
hydrogen  and  oxygen  are  in  the  same  proportion  to  each  other, 
that  is,  in  the  proportion  to  form  water. 

We  should  naturally  expect  that  the  flame  given  out  by  de- 
cayed wood  should  be  more  brilliant  in  proportion  to  the  increase 
of  its  carbon,  but  we  find,  on  the  contrary,  that  it  burns  like 
tinder,  exactly  as  it  no  hydrogen  were  present.  For  the  pur- 
poses of  fuel,  decayed  or  diseased  wood  is  of  little  value,  for  it 
does  not  possess  the  property  of  burning  with  flame — a  property 
upon  which  the  advantages  of  common  wood  depend.  The 
hydrogen  of  decayed  wood  must,  consequently,  be  supposed  to 
bs  in  the  state  of  water ;  for  had  it  any  other  form,  the  charac- 
ters we  have  descj-ibed  would  not  be  possessed  by  the  decayed 
wood. 

If  we  suppose  decay  to  proceed  in  a  liquid  containing  much 
carbon  and  hydrogen,  then  a  compound  with  still  more  carbon 
must  be  formed,  in  a  manner  similar  to  the  production  of  the 
crystalline  colorless  naphthalin  from  a  gaseous  compound  of  car- 
bon and  hydrogen.  And  if  tiie  compound  thus  formed  were 
itself  to  undergo  further  decay,  the  final  result  must  be  the  sepa- 
ration of  carbon  in  a  crystalline  form. 

Science  can  point  to  no  process  capable  of  accounting  for  the 


DECAY  OF  WOODY  FIBRE.  34» 

origin  and  formation  of  diamonds,  except  the  process  of  decay. 
Diamonds  cannot  be  produced  by  the  action  of  fire ;  for  a  high 
temperature,  and  the  presence  of  oxygen  gas,  would  call  into 
play  their  combustibility.  But  there  is  the  greatest  reason  to 
believe  that  they  are  formed  in  the  humid  way — that  is,  in  a 
liquid,  and  the  process  of  decay  is  the  only  cause  to  which  their 
formation  can  with  probability  be  ascribed. 

Amber,  fossil  resin,  and  the  acids  in  mellite,  are  the  products 
of  vegetable  matter  which  has  suffered  eremacausis.  They  are 
found  in  wood  (or  brown)  coal,  and  have  evidently  proceeded 
from  the  decomposition  of  substances  which  were  contained  in 
quite  a  different  form  in  the  living  plants.  They  are  all  distin- 
guished by  their  proportionally  small  quantity  of  hydrogen.  The 
acid  from  mellite  (mellitic  acid)  contains  precisely  the  same  pro- 
portions of  carbon  and  oxygen  as  that  from  amber  (succinic 
acid)  ;  they  differ  only  in  the  proportion  of  their  hydrogen. 
Succinic  acid  may  be  obtained  by  oxidation  from  wax  and  all 
other  solid  fats. 


^344  VEGETABLE  MOULD. 


CHAPTER  XII. 

Vegetable  Mjuld. 

The  term  vegetable  mould,  in  its  general  signification,  is 
applied  to  a  mixture  of  disintegrated  minerals,  with  the  remains 
of  animal  and  vegetable  substances.  It  may  be  considered  as 
earth  in  which  humus  is  contained  in  a  state  of  decomposition. 
Its  action  upon  the  air  has  been  fully  investigated  by  Ingenhouss 
and  De  Saussure. 

When  moist  vegetable  mould  is  placed  in  a  vessel  full  of  air,  it 
extracts  the  oxygen  therefrom  with  greater  rapidity  than  decayed 
wood,  and  replaces  it  by  an  equal  volume  of  carbonic  acid. 
"When  this  carbonic  acid  is  removed,  and  fresh  air  admitted,  the 
same  action  is  repeated. 

Cold  water  dissolves  only  -f  o  o  o  o'^^  of  its  own  weight  of  vege- 
table mould ;  the  solution  is  clear  and  colorless,  and  the  residue 
left  on  its  evaporation  consists  of  common  salt  with  traces  of  sul- 
phate of  potash  and  lime  and  a  minute  quantity  of  organic  mat- 
ter, for  it  is  slightly  blackened  when  heated  to  redness.  Boiling 
water  extracts  several  substances  from  vegetable  mould,  and 
acquires  a  yellow  or  yellowish  brown  color,  which  is  dissipated 
by  absorption  of  oxygen  from  the  air,  a  black  flocculent  deposit 
being  formed.  When  the  colored  solution  is  evaporated,  a 
residue  is  left  which  becomes  black  on  being  heated  to  redness, 
and  afterwards  yields  carbonate  of  potasii  when  treated  with 
water. 

A  solution  of  caustic  potash  becomes  black  when  placed  in 
contact  with  vegetable  mould,  and  the  addition  of  acetic  acid  to 
the  colored  solution  causes  no  precipitate  or  turbidity.  But 
dilute  sulphuric  acid  throws  down  a  light  flocculent  precipitate 
of  a  brown  or  black  color,  from  which  the  acid  can  be  removed 
with  difliculty  by  means  of  water.     When  this  precipitate,  after 


VEGETABLE  MOULD.  345 


having  been  washed  with  water,  is  brought  whilst  still  moist 
under  a  receiver  filled  with  oxygen,  the  gas  is  absorbed  with 
great  rapidity  ;  and  the  same  thing  takes  place  when  the  pre- 
cipitate is  dried  in  the  air.  In  the  perfectly  dry  state  it  has  en- 
tirely lost  its  solubility  in  water,  and  even  alkalies  dissolve  only 
traces  of  it. 

It  is  evident,  therefore,  that  boiling  water  extracts  a  matter 
from  vegetable  mould,  which  owes  its  solubility  to  the  presence 
of  the  alkaline  salts  contained  in  the  remains  of  plants.  This 
snbstance  is  a  product  of  the  incomplete  decay  of  woody  fibre, 
and  contains  a  certain  quantity  of  ammonia  chemically  combined. 
Its  composition  is  intermediate  between  woody  fibre  and  humu^, 
into  which  it  is  converted,  by  being  exposed  in  a  moist  condition 
.o  the  action  of  the  air. 


346  MOULDERING  OF  BODIES. 


CHAPTER  XIII. 

On  the  Mouldering  of  Bodies, — Paper,  Brown  Coal,  and  Mineral  Coal. 

The  decomposition  of  wood,  woody  fibre,  and  all  vegetable  bodies 
when  subjected  to  the  action  of  water,  and  excluded  from  the  air, 
is  termed  mouldering. 

Wcod  (or  brown  coal)  and  mineral  coal,  are  the  remains  of 
vegetables  of  a  former  world ;  their  appearance  and  characters 
show  that  they  are  products  of  the  processes  of  decomposition 
termed  decay  and  putrefaction.  We  can  easily  ascertain  by  ana- 
lysis the  manner  in  which  their  constituents  have  been  changed, 
if  we  suppose  the  greater  part  of  their  bulk  to  have  been  formed 
from  woody  fibre. 

But  it  is  necessary,  before  we  can  obtain  a  distinct  idea  of  the 
manner  in  which  coal  is  formed,  to  consider  a  peculiar  change 
which  woody  fibre  suffers  by  means  of  moisture,  when  partially 
or  entirely  excluded  from  the  air. 

It  is  known  that  when  pure  woody  fibre,  as  linen,  for  example, 
is  placed  in  contact  with  water,  considerable  heat  is  evolved,  and 
the  substance  is  converted  into  a  soft  friable  mass,  which  has  in 
a  great  degree  lost  its  coherence.  This  substance  was  employed 
in  the  fabrication  of  paper  before  the  use  of  chlorine,  as  an  agent 
for  bleaching.  The  rags  employed  for  this  purpose  were  placed 
in  heaps ;  and  it  was  observed,  that  on  their  becoming  warm  a 
gas  was  disengaged,  and  their  weight  diminished  from  18  to  25 
per  cent. 

When  sawdust  moistened  with  water  is  placed  in  a  closed 
vessel,  carbonic  acid  gas  is  evolved  in  the  same  manner  as  when 
air  is  admitted.  A  true  putrefaction  takes  place,  the  wood  as- 
sumes a  white  color,  loses  its  peculiar  texture,  and  is  converted 
into  a  rotten  friable  matter. 
.    The  white  decayed  wood   found  in  the  interior  of  trunks  of 


DECOMPOSITION  OF  WOOD,  COAL,  ETC.  34f 


dead  trees  which  have  been  in  contact  with  water,  is  produced 
in  the  way  just  mentioned. 

An  analysis  of  wood  of  this  kind,  obtained  from  the  interior 
of  the  trunk  of  an  oak,  yielded,  after  having  been  dried  at  212*=*, 


Carbon 

-     4711 

. 

. 

-    48-14 

Hydrogen 

-       6-31 

- 

- 

-       6-06 

Oxygen 

-     45-31 

- 

- 

-    44-43 

Ashes 

-       1  27 

- 

- 

-       1-37 

10000  100-00 

Now,  on  comparing  the  proportions  obtained  from  these  num- 
bers with  the  composition  of  oak  wood,  according  to  the  analysis 
of  Gay-Lussac  and  Thenard,  it  is  immediately  perceived  that  a 
certain  quantity  of  carbon  has  been  separated  from  the  constitu- 
ents of  wood,  whilst  the  hydrogen  is,  on  the  contrary,  increased. 
The  numbers  obtained  by  the  analysis  correspond  very  nearly  to 
the  formula  C33  Hg ,   034.* 

The  elements  of  water  have,  therefore,  along  with  a  certain 
amount  of  oxygen  from  the  air,  become  united  with  the  wood, 
whilst  carbonic  acid  is  separated  from  it. 

If  the  elements  of  5  atoms  of  water  and  3  atoms  of  oxygen  be 
added  to  the  composition  of  the  woody  fibre  of  the  oak,  and  three 
atoms  of  .carbonic  acid  deducted,  the  exact  formula  for  white 
mouldered  wood  is  obtained. 


Wood 

/o  this  add  5  atoms  of  water 

: 

C,.  H„  0 
-            H,   0 

3  atoms  of  oxygen    - 

- 

0 

C,.   H„   0,. 


Subtract  from  this  3  atoms  carbonic  acid    C    ^  O   ^ 


C,sHa7    ^4 


The  process  of  mouldering  is,  therefore,  one  of  putrification 
and  decay,  proceeding  simultaneously,  in  which  the  oxygen  of 

•  The  calculation  from  this  formula  gives  in  100  parts  47-9  carbon,  6-1 
bjfdrogen,  and  46  oxygen. 


348  MOULDERING  OF  BODIES. 

the  air  and  the  component  parts  of  water  take  part.  But  the 
composition  of  mouldered  wood  must  change  according  as  the 
access  of  oxygen  is  more  or  less  prevented.  White  mouldered 
beech-wood  yielded  on  analysis  47*67  carbon,  5*67,  hydrogen, 
and  46-68  oxygen;  this  corresponds  to  the  formula  C,,  Hgg 

o,.. 

The  decomposition  of  wood  assumes,  therefore,  two  different 
forms,  according  as  the  access  of  the  air  is  free  or  restrained. 
In  both  cases  carbonic  acid  is  generated  ;  and  in  the  latter  case, 
a  certain  quantity  of  water  enters  into  chemical  combination. 

It  is  highly  probable  that  in  this  putrefactive  process,  as  well 
as  in  all  others,  the  oxygen  of  the  water  assists  in  the  formation 
of  the  carbonic  acid. 

Wood-coal  (brown  coal  of  Werner)  must  have  been  produced 
by  a  process  of  decomposition  similar  to  that  of  mouldering. 
But  it  is  not  easy  to  obtain  wood-coal  suited  for  analysis,  for  it 
is  generally  impregnated  with  resinous  or  earthy  substances,  by 
which  the  composition  of  those  parts  which  have  been  formed 
from  woody  fibre  is  essentially  changed. 

The  wood-coal,  which  forms  extensive  layers  in  the  Wetterau 
(a  district  in  Hesse-Darmstadt),  is  distinguished  from  that  found 
in  other  places,  by  possessing  the  structure  of  wood  unchanged, 
and  by  not  containing  bituminous  matter.  This  coal  was  sub- 
jected to  analysis,  a  piece  being  selected  upon  which  the  annual 
circle  could  be  counted.  It  was  obtained  from  the  vicinity  of 
Laubach  ;   100  parts  contained 

Carbon 57'28 

Hydrogen 603 

Oxygen 36-]  0 

Ashes 0*59 


100-00 


The  large  amount  of  carbon,  and  small  quantity  of  oxygen, 
constitute  the  most  obvious  difference  between  this  analysis  and 
that  of  wood.  It  is  evident  that  the  wood  which  has  undergone 
the  change  into  coal  must  have  parted  with  a  certain  portion  of 


FORMATION  OF  WOOD  COAL.  349 

its  oxygen.     The  proportion  of  these  numbers  is  expressed  by 
the  formula  C3,   H^j   Oie-* 

When  these  numbers  are  compared  with  those  obtained  by 
the  analysis  of  oak,  it  would  appear  that  the  brown  coal  was  pro. 
duced  from  woody  fibre  by  the  separation  of  one  equivalent 
of  hydrogen,  and  the  elements  of  three  equivalents  of  carbonic 
acid. 

1  atom  wood C36H22O22 

Minus  1  atom  hydrogen  and  3  atoms  car-  \      n       xj      n 
bonicacid  .  .         .         ^      C    s  W    1^    « 

Wood  Coal        .      C33H21O16 

All  varieties  of  wood-coal,  from  whatever  strata  they  may  be 
taken,  contain  more  hydrogen  than  wood  does,  and  less  oxygen 
than  is  necessary  to  for.n  water  with  this  hydrogen  ;  conse- 
quently they  must  all  be  produced  by  the  same  process  of  decom- 
position. The  excess  of  hydrogen  is  either  hydrogen  of  the  wood 
remaining  in  it  unchanged,  or  it  is  derived  from  some  exterior 
source..  The  analysis  of  wood-coal  from  Ringkuhl,  near  Cassel, 
where  it  is  seldom  found  in  pieces  with  the  structure  of  wood, 
gave,  when  dried  at  212°, 

Carbon  .  .         .     62-60     . 
Hydrogen  .         .  5  02 

Oxygen  .  .         .     26  52     . 

Ashes         .         .  5 '86 


63-83 

4-80 

25  51 

5-86 

10000  10000 

The  proportions  derived  from  tiiese  numbers  correspond  very 
closely  to  the  formula  C,2  Hig  O^,  or  they  represent  the  con- 
stituents of  wood,  from  which  the  elements  of  carbonic  acid, 
Water,  and  2  equivalents  hydrogen,  have  been  separated. 

C,«  H22  02  2=Wood. 
Subtract  C    4  H    7  Oi  3=4  atoms  carbonic  acid +  5  atoms  of  water 
+2  atoms  of  hydrogen. 

C 1 2  H 1  5  O    9  =Wood  Coal  from  Ringkuhl. 
t  •  The  calculation  givew  57-5  carbon,  and  5-98  hydrogen. 


350  CONVERSION  OF  WOOD 

The  formation  of  both  these  specimens  of  wood-coal  appears 
from  these  formulae  to  have  taken  place  under  circumstances 
which  did  not  entirely  exclude  the  action  of  the  air,  and  conse- 
quent oxidation  and  removal  of  a  certain  quantity  of  hydrogen. 
Now  the  Laubacher  coal  is  covered  with  a  layer  of  basalt,  and 
the  coal  of  Ringkuhl  was  taken  from  the  lowest  seam  of  layers, 
which  possess  a  thickness  of  from  90  to  120  feet ;  so  that  both 
may  be  considered  as  well  protected  from  the  air. 

During  the  formation  of  brown  coal,  therefore,  the  elements  of 
carbonic  acid  have  been  separated  from  the  wood  either  alone, 
or  at  the  same  time  with  a  certain  quantity  of  water.  It  is  quite 
possible  that  the  difference  in  the  process  of  decomposition  may 
depend  upon  the  high  temperature  and  pressure  under  which  the 
decomposition  took  place.  At  least,  a  piece  of  wood  assumed  the 
character  and  appearance  of  Laubacher  coal,  after  being  kept 
for  several  weeks  in  the  boiler  of  a  steam-engine,  and  had  then  a 
very  similar  composition.  The  change  in  this  case  was  effected 
in  water,  at  a  temperature  of  from  334°  to  352°  F.  (150^  to  160° 
C),  and  under  a  corresponding  pressure.  The  ashes  of  the  wood 
amounted  to  0-51  per  cent.;  a  little  less,  therefore,  than  these  of 
the  Laubacher  coal  ;  but  this  must  be  ascribed  to  the  peculiar 
circumstances  under  which  it  was  formed.  The  ashes  of  plants 
examined  by  Berthier  amounted  always  to  much  more  than  this. 

The  peculiar  process  by  ^vhich  the  decomposition  of  these 
extinct  vegetables  has  been  effected,  namely,  a  disengagement 
of  carbonic  acid  from  their  substance,  appears  still  to  go  on  at 
great  depths  in  all  the  layers  of  wood- coal.  At  all  events,  it  is 
remarkable  that  springs  impregnated  with  carbonic  acid  occur  in 
many  places,  in  the  country  between  the  Meissner,  in  the  electorate 
of  Hesse,  and  the  Eifel,  which  are  known  to  possess  large  layers 
of  wood-coal.  These  springs  of  mineral  water  are  produced  on 
the  spot  at  which  they  are  found ;  the  springs  of  common  water 
meeting  with  carbonic  acid  during  their  ascent,  and  becoming 
impregnated  with  it. 

In  the  vicinity  of  the  layers  of  wood-coal  at  Salzhausen 
(Hesse-Darmstadt),  an  excellent  acidulous  spring  of  this  kind 
existed  a  few  years  ago,  and  supplied  all  the  inhabitants  of  that 
district;  but  it  was  CQnsidered  advantageous  to  surround  tbo 


INTO  BROWN  OR  WOOD- COAL.  3iil 


sides  of  the  spring  with  sandstone,  and  the  consequence  was,  that 
all  the  outlets  to  the  carbonic  acid  were  closed,  for  this  gas 
generally  gains  access  to  the  water  from  the  sides  of  the  spring. 
From  that  time  to  the  present  this  valuable  mineral  water  has 
disappeared,  and  in  its  place  is  found  a  spring  of  common 
water. 

Springs  of  water  impregnated  with  carbonic  acid  occur  at 
Schwalheim,  at  a  very  short  distance  from  the  layers  of  wood-coal 
at  Dorheim.  M.  Wilhelmi  observed  some  time  since,  that  they 
are  formed  of  common  spring  water,  which  ascends  from  below, 
and  of  carbonic  acid,  which  issues  from  the  sides  of  the  spring. 
The  same  fact  has  been  shown  to  be  the  case  in  the  famed 
Fachinger  spring,  by  M.  Schapper. 

The  carbonic  acid  gas  from  the  springs  in  the  Eifel  is,  accord- 
ing to  BischofF.  seldom  mixed  with  nitrogen  or  oxygen,  and  is 
probably  produced  in  a  manner  similar  to  that  just  described. 
At  any  rate,  the  air  does  not  appear  to  take  any  part  in  the 
formation  of  these  acidulous  springs.  Their  carbonic  acid  has 
evidently  not  been  formed  either  by  a  combustion  at  high  or  low 
temperatures  ;  for  if  it  were  so  the  gas  resulting  from  the  com- 
bustion would  necessarily  be  mixed  with  f  of  nitrogen,  but  it 
does  not  contain  a  trace  of  this  element.  The  bubbles  of  gas 
which  escape  from  these  springs  are  absorbed  by  caustic  potash, 
with  the  exception  of  a  residuum  too  small  to  be  appreciated. 

The  wood-coal  of  Dorheim  and  Salzhausen  must  have  been 
formed  in  the  same  way  as  that  of  the  neighboring  village 
of  Laubach  ;  and  since  the  latter  contains  the  exact  elements  of 
woody  fibre,  minus  a  certain  quantity  of  carbonic  acid,  its  com- 
position indicates  very  plainly  the  manner  in  which  it  has  been 
produced. 

The  coal  of  the  upper  bed  is  subjected  to  ar  incessant  decay 
by  the  action  of  the  air,  by  means  of  which  its  hydrogen 
is  renwved  in  the  same  manner  as  in  the  decay  of  wood.  This 
is  recognised  by  the  way  in  which  it  burns,  and  by  the  formation 
of  carbonic  acid  in  the  mines. 

The  gases  which  are  formed  in  mines  of  wood- coal,  and  cause 
danger  in  their  working,  are  not  combustible  or  inflammable  as 
in  mines  of  mineral  coal ;  but  they  consist  generally  of  carbonio: 


552  CONVERSION  OF  WOOD 

acid  gas,  and  are  very  seldom  intermixed  with  combustible 
gases. 

Wood-coal  from  the  middle  bed  of  the  strata  at  Ringkuhl  gave 
on  analysis  65'40 — 64*01  carbon,  and  4*75 — 4-76*  hydrogen ; 
the  proportion  of  carbon  here  is  the  same  as  in  specimens 
procured  from  greater  depths,  but  that  of  the  hydrogen  is  much 
less. 

Wood  and  mineral  coal  are  always  accompanied  by  iron 
pyrites  (sulphuret  of  iron)  or  zinc  blende  (sulphuret  of  zinc) ; 
which  minerals  are  still  formed  from  salts  of  sulphuric  acid,  with 
iron  or  zinc,  during  the  putrefaction  of  all  vegetable  matter.  It 
is  possible  that  the  oxygen  of  the  sulphates  in  the  layers  of  wood- 
coal  is  the  means  by  which  the  removal  of  the  hydrogen,  is 
effected,  since  wood-coal  contains  less  of  this  element  than  wood. 

According  to  the  analysis  of  Richardson  and  Regnault,  the 
composition  of  the  combustible  materials  in  splint  coal  from 
Newcastle,  and  cannel  coal  from  Lancashire,  is  expressed  by  the 
formula  C.^^  Hj,  O.  When  this  is  compared  with  the  composi- 
tion of  woody-fibre,  it  appears  that  these  coals  are  formed  from 
its  elements,  by  the  removal  of  a  certain  quantity  of  carburetted 
hydrogen  and  carbonic  acid,  in  the  form  of  combustible  oils. 
The  composition  of  both  of  these  coals  is  obtained  by  the  subtrac- 
tion of  3  atoms  of  carburetted  hydrogen,  three  atoms  of  water, 
and  9  atoms  of  carbonic  acid  from  the  formula  of  wood. 

:wood 
3  atoms  of  carburetted  hydrogen  C  s  H    e 
3  atoms  of  water         .         .         .  H  3  O    3 
9  atoma  of  carbonic  acid         .       C  9  O  i  g 


Mineral  coal 


C12H     9021 

C24  H13O 


Carburetted  hydrogen  generally  accompanies  all  mineral  coal ; 
other  varieties  of  coal  contain  volatile  oils  which  may  be  sepa- 
rated by  distillation  with  water.  (Reichenbach.)  This  origin  of 
naphtha  is  owing  to  a  similar  process  of  decomposition.  Caking 
coal  from  Caresfield,  near  Newcastle,  contains  the  elements  of 
cannel  coal,  minus  the  constituents  of  defiant  gas  C4  H4. 

•  The  analysis  of  brown  coal  from  Ringkuhl,  as  well  as  all  those  of  the 
fame  substance  given  in  this  work,  have  been  executed  in  this  laboratory 
hy  M.  Khiinert,  of  Cassel. 


INTO  MINERAL  COAL.  353 

The  iniSammable  gases  which  stream  out  of  clefts  in  the  strata 
of  mineral  coal,  or  in  rocks  of  the  coal  formations,  always  con- 
tain carbonic  acid,  according  to  a  recent  examination  by  Bischoff, 
and  also  carburetted  hydrogen,  nitrogen,  and  defiant  gas  ;  the 
last  of  which  had  not  been  observed,  until  its  existence  in  these 
gases  was  pointed  out  by  Bischoff.  The  analysis  of  Jire-dampf 
after  it  had  been  treated  with  caustic  potash,  showed  its  consti- 
tuents to  be — 


Gas  from  an 

abandoned 

Gerhard's  pas- 

Gas from  a 

n.ine  near 

sage  near 

mine  near 

Walleswsiller. 

Luisenthal.  • 

Liekwege. 

Vol. 

FoL 

FoL 

Light  carburetted  hydrogen     91 -3^ 

8308 

89-10 

Olefiant  gas        -         -       6-32 

1-98 

6-11 

Nitrogen  gas     -         -       2-32 

14-94 

4-79 

10000  10000  100-00 

The  evolution  of  these  gases  proves  that  changes  are  constantly 
proceeding  in  the  coal. 

It  is  obvious  from  this,  that  a  continual  removal  of  oxygen  in 
the  form  of  carbonic  acid  is  effected  from  layers  of  wood-coal, 
in  consequence  of  which  the  wood  must  approach  gradually  to 
the  composition  of  mineral  coal.  Hydrogen,  on  the  contrary,  is 
disengaged  from  the  constituents  of  mineral  coal  in  the  form  of 
a  compound  of  hydro-carbon  ;  a  complete  removal  of  all  the 
hydrogen  would  convert  coal  into  anthracite. 

The  formula  C,e  R^^  Ojg,  which  is  given  for  wood,  has  been 
chosen  as  the  empirical  expression  ot  the  analysis,  for  the  pur- 
pose of  bringing  all  the  transformations  which  woody  fibre  is 
capable  of  undergoing  under  one  common  point  of  view. 

Now,  although  the  correctness  of  this  formula  must  be  doubted, 
until  we  know  with  certainty  the  irue  constitution  of  woody  fibre, 
this  cannot  have  the  smallest  influence  on  the  account  given  of 
the  changes  to  which  wood  fibre  must  necessarily  be  subjected 
in  order  to  be  converted  into  wood  or  mineral  coal.  The  theore- 
lical  expression  refers  to  the  absolute  quantity,  the  empirical 
merely  to  the  relative  proportion,  in  which  the  elements  of  a  body 
are  united.  Whatever  form  the  first  may  assume,  the  empirical 
expression  must  always  remain  unchanged. 


W4  POISONS,  CONTAGIONS,  MIASMS. 


chapti:r  XV. 

On  Poisons,  Contagions,  and  Miasms. 

A  GREAT  many  chemical  compounds,  some  derived  from  inorganic 
nature,  and  others  formed  in  animals  and  plants,  produce  pecu- 
liar changes  or  diseases  in  the  living  animal  organism.  They 
disturb  the  vital  functions  of  individual  organs ;  and  when  their 
action  attains  a  certain  degree  of  intensity,  death  is  the  conse- 
quence. 

The  action  of  inorganic  compounds,  such  as  acids,  alkalies, 
metallic  oxides,  and  salts,  can  in  most  cases  be  easily  explained. 
They  either  destroy  the  continuity  of  particular  organs,  or  they 
enter  into  combination  with  their  substance.  The  action  of  sul- 
phuric, muriatic,  and  oxalic  acids,  hydrate  of  potash,  and  all 
those  substances  which  produce  the  direct  destruction  of  the 
organs  with  which  they  come  into  contact,  may  be  compared  to 
a  piece  of  iron,  which  can  cause  death  by  inflicting  an  injury 
on  particular  organs,  either  when  heated  to  redness,  or  when  in 
the  form  of  a  sharp  knife.  Such  substances  are  not  poisons 
in  the  limited  sense  of  the  word,  for  their  injurious  action  depends 
merely  upon  their  condition. 

The  action  of  the  proper  inorganic  poisons  is  owing,  in  most 
cases,  to  the  formation  of  a  chemical  compound  by  the  union  of 
the  poison  with  the  constituents  of  the  organ  upon  which  it  acts ; 
it  is  owing  to  an  exercise  of  a  chemical  affinity  more  powerful 
than  the  vitality  of  the  organ. 

It  is  well  to  consider  the  action  of  inorganic  substances  in 
general,  in  order  to  obtain  a  clear  conception  of  the  mode  of 
action  of  those  which  are  poisonous.  We  find  that  certain 
soluble  compounds,  when  presented  to  different  parts  of  the  body, 
are  absorbed  by  the  blood,  wljcncc  they  are  again  eliminated 


EFFECTS  OF  SALTS  ON  THE  ORGANISM.  355 

by  the  organs  of  secretion,  either  in  a  changed  or  in  an  un- 
changed state. 

Iodide  of  potassium,  sulpho-cyanuret  of  potassium,  ferro- 
cyanuret  of  potassium,  chlorate  of  potash,  silicate  of  potash,  and 
all  salts  with  alkaline  bases,  when  administered  internally  to  man 
and  animals  in  dilute  solutions,  or  applied  externally,  may  be 
again  detected  in  the  blood,  sweat,  chyle,  gall,  and  splenic  veins  ; 
l>ut  all  of  them  are  finally  excreted  from  the  body  through  the 
urinary  passages. 

Each  of  these  substances,  in  its  transit,  produces  a  peculiar 
disturbance  in  the  organism — in  other  words,  they  exercise  a 
medicinal  action  upon  it,  but  they  themselves  suffer  no  decom- 
position. If  any  of  these  substances  enter  into  combination  with 
any  part  of  the  body,  the  union  cannot  be  of  a  permanent  kind  ; 
for  their  re-appearance  in  the  urine  shows  that  any  compounds 
thus  formed  must  have  been  again  decomposed  by  the  vital 
processes. 

Neutral  citrates,  acetates,  and  tartrates  of  the  alkalies  suffer 
change  in  their  passage  through  the  organism.  Their  bases  can 
indeed  be  detected  in  the  urine,  but  the  acids  have  entirely  dis- 
appeared, and  arc  replaced  by  carbonic  acid,  which  has  united 
with  the  bases.     (Gilbert  Blane  and  Wcihler.) 

The  conversion  of  these  salts  of  organic  acids  into  carbonates, 
indicates  that  a  considerable  quantity  of  oxygen  must  have 
united  with  their  elements.  In  order  to  convert  one  equivalent 
of  acetate  of  potash  into  the  carbonate  of  the  same  base,  8  equi- 
A'alents  of  oxygen  must  combine  with  it,  of  which  either  2  or  4 
.equivalents  (according  as  an  acid  or  neutral  salt  is  produced) 
remain  in  combination  with  the  alkali ;  whilst  the  remaining  G 
or  4  equivalents  are  disengaged  as  free  carbonic  acid.  There  is 
no  evidence  presented  by  the  organism  itself,  to  which  these  salts 
hAve  been  administered,  that  any  of  its  proper  constituents  have 
yielded  so  great  a  quantity  of  oxygen  as  is  necessary  for  their 
{conversion  into  carbonates.  Their  oxidation  can,  therefore,  only 
he  ascribed  to  the  oxygen  of  the  air. 

During  the  passage  of  these  salts  through  the  lungs,  their 
acids  take  part  in  the  peculiar  process  of  eremacausis  proceed- 
irg  in  that  organ  ;  a  certain  quantity  of  the  oxygen  gas  inspired 


856  POISONS,  CONTAGIONS,  MIASMS. 

unites  with  their  constituents,  ami  converts  their  hydrogen  into 
water,  and  their  carbon  into  carbonic  acid.  Part  of  this  latter 
product  (1  or  2  equivalents)  remains  in  combination  with  the 
alkaline  base,  forming  a  salt  which  suffers  no  further  change  by 
the  process  of  oxidation  ;  and  it  is  this  salt  which  is  separated  by 
the  kidneys  or  liver. 

It  is  manifest  that  the  presence  of  these  organic  salts  in  the 
blood  must  produce  a  change  in  the  process  of  respiration.  A 
part  of  the  oxygen  inspired,  which  usually  combines  with  the 
constituents  of  the  blood,  must,  when  they  are  present,  combine 
with  their  acids,  and  thus  be  prevented  from  performing  its 
usual  office.  The  immediate  consequence  of  this  must  be  the 
formation  of  arterial  blood  in  less  quantity,  or,  in  other  words, 
the  process  of  respiration  must  be  retarded. 

Neutral  acetates,  tartrates,  and  citrates  placed  in  contact  with 
the  air,  and  at  the  same  time  with  animal  or  vegetable  bodies  in 
a  state  of  eremacausis,  produce  exactly  the  same  effects  as  ws 
have  described  them  to  produce  in  the  lungs.  They  participate 
in  the  process  of  decay,  and  are  converted  into  carbonates  just  as 
in  the  living  body.  If  impure  solutions  of  these  salts  in  water 
are  left  exposed  to  the  air  for  any  length  of  time,  their  acids  are 
gradually  decomposed,  and  at  length  entirely  disappear. 

Free  mineral  acids,  or  organic  acids  without  volatility,  and 
salts  of  mineral  acids  with  alkaline  bases,  completely  arrest 
decay  when  added  to  decaying  matter  in  sufficient  quantity  ; 
and  when  their  quantity  is  small,  the  process  of  decay  is  pro- 
tracted and  retarded.  They  produce  in  living  bodies  the  same 
phenomena  as  the  neutral  organic  salts,  but  their  action  depends 
upon  a  different  cause. 

The  absorption  by  the  blood  of  a  quantity  of  an  inorganic  salt 
sufficient  to  arrest  the  process  of  eremacausis  in  the  lungs,  is 
prevented  by  a  very  remarkable  property  of  all  animal  mem- 
branes,  skin,  cellular  tissue,  muscular  fibre,  &c.  ;  namely,  bv 
their  incapability  of  being  permeated  by  concentrated  sa'ino 
solutions.  It  is  only  when  these  solutions  are  diluted  to  a 
certain  degree  with  water  that  they  are  absorbed  by  animal 
tissues. 

A  dry   bladder  remains  more  or  less  dry  in  saturated  souN 


EBTECTS  OF  SALTS  ON  THE  ORGANISM.  35" 

tions  of  common  salt,  nitre,  ferro-cyanuret  of  potassium,  sulpho- 
cyanuret  of  potassium,  sulphate  of  magnesia,  chloride  of  potas- 
sium, and  sulphate  of  soda.  These  solutions  run  off  its  surface 
in  the  same  manner  as  water  runs  from  a  plate  of  glass  be- 
smeared with  tallow. 

Fresh  flesh,  over  which  salt  has  been  strewed,  is  found, 
after  24  hours,  swimming  in  brine,  although  not  a  drop  of  water 
has  been  added.  The  water  has  been  yielded  by  the  muscular 
fibre  itself,  and  having  dissolved  the  salt  in  immediate  contact 
with  it,  and  thereby  lost  the  power  of  penetrating  animal  sub- 
stances, it  has  on  this  account  separated  from  the  flesh.  The 
water  still  retained  by  the  flesh  contains  a  proportionally  small 
quantity  of  salt,  having  that  degree  of  dilution  at  which  a  saline 
fluid  is  capable  of  penetrating  animal  substances. 

This  property  of  animal  tissues  is  taken  advantage  of  in 
domestic  economy  for  the  purpose  of  removing  so  much  water 
from  meat  that  a  sufficient  quantity  is  not  left  to  enable  it  to 
enter  into  putrefaction. 

In  respect  of  this  physical  property  of  animal  tissues,  alcohol 
resembles  the  inorganic  salts.  It  is  incapable  of  moistening,  that 
is,  of  penetrating,  animal  tissues,  and  possesses  such  an  affinity 
for  water  as  to  extract  it  from  moist  substances. 

When  a  solution  of  a  salt,  in  a  certain  degree  of  dilution,  is  in- 
troduced into  the  stomach,  it  is  absorbed ;  but  a  concentrated 
saline  solution,  in  place  of  being  itself  absorbed,  extracts  water 
from  the  organ,  and  a  violent  thirst  ensues.  Some  interchange 
of  water  and  salt  takes  place  in  the  stomach  ;  the  coats  of  this 
viscus  yield  water  to  the  solution,  a  part  of  which,  having  pre- 
viously become  sufficiently  diluted,  is,  on  the  other  hand,  ab- 
sorbed. But  the  greater  part  of  the  concentrated  solution  of  salt 
remains  unabsorbed,  and  is  not  removed  by  the  urinary  pas- 
sages ;  it  consequently  enters  the  intestines  and  intestinal  canal, 
where  it  causes  a  dilution  of  '.he  solid  substances  deposited 
there,  and  thus  acts  as  a  purgative. 

Each  of  the  salts  just  mentioned  possesses  this  purgative 
action,  which  depends  on  a  physical  property  shared  by  all  of 
them  ;  but,  besides  this,  they  exercise  a  medicinal  action,  be« 


.«M  POISONS,  CONTAGIONS,  MIASMS. 


cause  every  part  of  the  organism  with  which  they  come  in  con- 
tact absorbs  a  certain  quantity  of  them. 

The  composition  of  the  salts  has  nothing  to  do  with  their  pur- 
gative action  ;  it  is  quite  a  matter  of  indiiference  as  far  as  the 
mere  production  of  this  action  is  concerned  (not  as  to  its  inten- 
sity), whether  the  base  be  potash  or  soda,  or  in  many  cases  lime 
.and  magnesia ;  and  whether  the  acid  be  phosphoric,  sulphuric, 
nitric,  or  hydrochloric. 

If  we  drink,  fasting,  a  glass  of  common  spring  water  every 
ten  minutes,  a  strong  diuretic  action  becomes  apparent,  the 
quantity  of  salts  in  the  water  being  much  less  than  that  in  ^hp 
blood.  '^ 

When  the  second  glass  is  taken,  a  quantity  of  urine  is  elimi- 
nated, the  weight  and  volume  of  which  corresponds  nearly  to 
that  of  the  first  glass ;  and  by  drinking  twenty  successive 
gUxsses  of  water,  nineteen  evacuations  of  urine  take  place,  the 
last  of  which  is  colorless,  and  scarcely  differs  in  its  amount  of 
saline  ingredients  from  the  spring  water  itself. 

When  the  same  experiment  is  made  with  a  water  contain- 
ing  exactly  the  amount  of  salts  as  in  blood  ( j  to  1  per  cent, 
of  common  salt  for  example),  a  separation  of  urine  is  not 
effected,  and  it  becomes  almost  impossible  to  drink  more 
than  three  glasses  of  such  water.  A  sensation  of  fulness 
in  the  stomach,  of  pressure  and  weight,  seems  to  show  that 
water  containing  an  equal  amount  of  saline  ingredients  as  blood, 
requires  a  much  longer  time  to  be  taken  up  by  the  blood- 
vessels. 

When  the  water  taken  contains  a  larger  amount  of  salts 
than  that  existing  in  blood,  a  more  or  less  active  purgative 
action  ensues.  Hence,  we  see  that  three  kinds  of  action  take 
place,  according  to  the  quantities  of  salt  existing  in  the  water. 

Besides  these  salts,  the  action  of  which  does  not  depend  upon 
their  power  of  entering  into  combination  with  the  component 
parts  of  the  organism,  there  is  a  large  class  of  others  which, 
when  introduced  into  the  living  body,  effect  changes  of  a  very 
different  kind,  and  produce  diseases  or  death,  according  to  the 
nature  of  these  changes,  without  effecting  a  visible  lesion  of  any 
organs. 


INORGANIC  POISONS  ..'550 


These  are  the  true  inorganic  poisons,  the  action  of  which  de- 
pends upon  their  power  of  forming  permanent  compounds  with 
the  substance  of  the  membranes  and  muscular  fibre. 

Salts  of  lead,  iron,  bismuth,  copper,  and  mercury,  belong  to 
this  class. 

When  solutions  of  these  salts  are  treated  with  a  sufficient 
quantity  of  albumen,  milk,  muscular  fibre,  and  animal  mem- 
branes, they  enter  into  combination  with  those  substances,  and 
lose  their  own  solubility  ;  while  the  water  in  which  they  were 
dissolved  loses  all  the  salt  which  it  contained. 

The  salts  of  alkaline  bases  extract  water  from  animal  sub- 
stances ;  whilst  the  salts  of  the  heavy  metallic  oxides  are,  on  the 
contrary,  extracted  from  the  water,  for  they  enter  into  combina- 
tion with  the  animal  matters. 

Now,  when  these  substances  are  administered  to  an  animal, 
they  lose  their  solubility  by  entering  into  combination  with 
the  membranes,  cellular  tissue,  and  muscular  fibre ;  but  in 
very  few  cases  can  they  reach  the  blood.  According  to  all 
the  experiments  yet  made  on  the  subject,  it  appears,  that  after 
the  lapse  of  the  same  time  as  is  required  for  the  appearance 
of  alkaline  salts  in  the  urine,  the  metallic  salts  above  mentioned 
cannot  be  detected  in  that  fluid.  In  fact,  during  their  passage 
through  the  organism,  they  come  into  contact  with  many  sub- 
stances by  which  they  are  retained.  By  degrees,  however,  the 
constituents  of  the  tissues  with  which  they  have  combined  are 
altered  by  the  change  of  matter ;  their  nitrogen  appears  in  the 
urine,  and  along  with  it  the  mineral  elements  previously  com- 
bined with  the  organic  matter,  such  as  mercury,  copper,  6zc. 
When  such  substances  enter  into  combination  with  organized 
parts,  the  functions  of  those  parts  must  be  disturbed,  and  must 
take  an  abnormal  direction,  producing  morbid  phenomena. 

The  action  of  corrosive  sublimate  and  arsenious  acid  is  very 
remarkable  in  this  respect.  Corrosive  sublimate  and  other 
salts  of  mercury  combine  chiefly  with  albumen  and  albuminous 
tissues. 

Arsenious  acid  enters  into  a  very  firm  combination  with  mem- 
branes and  gelatinous  tissues.  A  piece  of  fresh  skin,  or  a  blad- 
der which,  if  covered  with  water,  liquefy  in  a  few  weeks  into  a 


360  POISOx\S,  CONTAGIONS,  MIASMS. 

fetid,  putrid  mass,  retain  all  their  properties  unchanged  if  ar 
senious  acid  be  added  to  the  water.  The  arsenious  acid,  combining 
with  these  tissues,  gives  to  them  the  power  of  resisting  decay 
and  putrefaction.  The  putrefaction  of  flesh,  or  of  blood,  and 
the  fermentation  of  sugar,  are  not  checked  or  prevented  by  ar- 
senious acid. 

It  is  further  known  that  the  parts  of  a  body  which  come  in  con- 
tact with  these  substances  during  poisoning,  and  which  therefore 
enter  into  combination  with  them,  do  not  afterwards  putrefy ;  so 
that  there  can  be  no  doubt  regarding  the  cause  of  their  poisonous 
qualities. 

It  is  obvious  that  if  arsenious  acid  and  corrosive  sublimate  are 
not  prevented  by  the  vital  principle  from  entering  into  combi- 
nation with  the  component  parts  of  the  body,  and  consequently 
from  rendering  them  incapable  of  decay  and  putrefaction,  they 
must  deprive  the  organs  of  the  principal  property  which  apper- 
tains to  their  vital  condition,  viz.  that  of  suffering  and  effecting 
transformations  ;  or,  in  other  words,  organic  life  must  be  de- 
stroyed. If  the  poisoning  is  merely  superficia);  and  the  -quantity 
of  the  poison  so  small  that  only  individual  parts  of  the  body  ca- 
pable of  being  regenerated  have  entered  into  combination  with  it, 
then  eschars  are  produced — a  phenomenon  of  a  secondary  kind 
— the  compounds  of  the  dead  tissues  with  the  poison  being  thrown 
off  by  the  healthy  parts.  From  these  considerations  it  may  readily 
be  inferred  that  all  internal  signs  of  poisoning  are  variable  and 
uncertain  ;  for  cases  may  happen,  in  which  no  apparent  indica- 
tion of  change  can  be  detected  by  simple  observations  of  the  parts, 
because,  as  has  been  already  remarked,  death  may  occur  without 
the  destruction  of  any  organs. 

When  arsenious  acid  is  administered  in  solution,  it  may  enter 
into  the  blood.  If  a  vein  is  exposed  and  surrounded  with  a  solu- 
tion of  this  acid,  every  blood-globule  will  combine  with  it,  that  is, 
will  become  poisoned. 

The  compounds  of  arsenic,  which  have  not  the  property  of  en- 
tering into  combination  with  the  tissues  of  the  organism,  are 
without  influence  on  life,  even  in  large  doses.  Many  insoluble 
basic  salts  of  arsenious  acid  are  known  not  to  be  poisonous.  The 
substance  called  alkargen,  discovered  by  Bunsen,  has  not  tho 


INORGANIC  POISON  &.  3<Jl 

slightest  injurious  action  upon  the  organism  ;  yet  it  contains  a 
very  large  quantity  of  arsenic,  and  approaches  very  closely  in 
composition  to  organic  compounds. 

These  considerations  enable  us  to  fix  with  tolerable  certainty 
the  limit  at  which  the  above  substances  cease  to  act  as  poisons. 
For  since  their  combination  with  organic  matters  must  be  regu- 
lated by  chemical  laws,  death  will  inevitably  result,  when 
the  organ  in  contact  with  the  poison  finds  sufficient  of  it  to 
unite  with  atom  for  atom ;  whilst  if  the  poison  is  present 
in  smaller  quantity,  a  part  of  the  organ  will  retain  its  vital 
functions. 

All  substances  administered  as  antidotes  in  cases  of  poisoning, 
act  by  destroying  the  power  which  arsenious  acid  and  corrosive 
sublimate  possess,  of  entering  into  combination  with  animal  mat 
ters,  and  of  thus  acting  as  poisons.  Unfortunately  no  other  body 
surpasses  them  in  that  power,  and  the  compounds  which  they 
form  can  only  be  broken  up  by  affinities  so  energetic,  that  their 
action  is  as  injurious  as  that  of  the  above-named  poisons  them- 
selves. The  duty  of  the  physician  consists,  therefore,  in  his 
causing  those  parts  of  the  poison  which  may  be  free  and  still  un- 
combined,  to  enter  into  combination  with  some  other  body,  so  as 
to  produce  a  compound  incapable  of  being  decomposed  or  digested 
in  the  same  conditions.  Hydrated  peroxide  of  iron  is  an  in- 
valuable substance  for  this  purpose. 

When  the  action  of  arsenious  acid  or  corrosive  sublimate  is 
confined  to  the  surface  of  an  organ,  those  parts  only  are  destroyed 
which  enter  into  combination  with  it ;  an  eschar  is  formed,  and 
is  gradually  thrown  off. 

Soluble  salts  of  silver  would  be  quite  as  deadly  a  poison  as 
corrosive  sublimate,  did  not  a  cause  exist  in  the  human  body  by 
which  their  action  is  prevented,  unless  their  quantity  is  very 
great.  This  cause  is  the  presence  of  common  salt  in  all  animal 
liquids.  Nitrate  of  silver,  it  is  well  known,  combines  with  ani- 
mal substances,  in  the  same  manner  as  corrosive  sublimate,  and 
the  compounds  formed  by  both  are  exactly  similar  in  the  character 
of  being  incapable  of  decay  or  putrefaction. 

When  nitrate  of  silver  in  a  state  of  solution  is  applied  to  skin 
or  muscular  fibre,  it  combines  with  them  instantaneously;  ahi- 
17 


S62  POISONS,  CONTAGIONS,  MIASMS. 

mal  substances  dissolved  in  any  liquid  are  precipitated  by  it,  and 
rendered  insoluble,  or,  as  it  is  usually  termed,  they  are  coagu- 
lated. The  compounds  thus  formed  are  colorless,  and  so  stable, 
that  they  cannot  be  decomposed  by  other  powerful  chemical 
agents.  They  are  blackened  by  exposure  to  light,  like  all  othei 
compounds  of  silver,  in  consequence  of  a  part  of  their  oxide  ol 
silver  being  reduced  to  the  metallic  state.  Parts  of  the  body 
united  to  salts  of  silver  no  longer  belong  to  the  living  organism, 
for  their  vital  functions  have  been  arrested  by  combination  with 
oxide  of  silver ;  and  if  they  are  capable  of  being  reproduced, 
the  neighboring  living  structures  throw  them  off  in  the  form  of  an 
eschar. 

When  nitrate  of  silver  is  introduced  into  the  stomach,  it  meets 
with  common  salt  and  free  muriatic  acid  ;  and  if  its  quantity  is 
not  too  great,  it  is  immediately  converted  into  chloride  of  silver 
— a  substance  absolutely  insoluble  in  pure  water.  In  a  solution 
of  salt  or  muriatic  acid,  however,  chloride  of  silver  does  dissolve 
in  extremely  minute  quantity ;  and  it  is  this  small  part  which 
exercises  a  medicinal  influence  when  nitrate  of  silver  is  ad- 
ministered :  the  remaining  chloride  of  silver  is  eliminated  from 
the  body  in  the  ordinary  way. 

Without  solubility,  or  the  power  of  being  carried  to  every  part 
of  the  circulation,  no  substance  possesses  activity  in  reference  to 
the  animal  organism. 

The  soluble  salts  of  lead  possess  many  properties  in  common 
with  the  salts  of  silver  and  mercury ;  but  all  compounds  of  lead 
with  organic  matters  are  capable  of  decomposition  by  dilute  sul- 
phuric acid.  The  disease  csilled painter's colicis  unknown  in  all 
manufactories  of  white  lead  in  which  the  workmen  are  accustomed 
to  take  as  a  preservative  sulphuric  acid  lemonade  (a  solution  of 
sugar  rendered  acid  by  sulphuric  acid). 

The  organic  substances  which  have  combined  in  the  living 
body  with  metallic  oxides  or  metallic  salts,  lose  their  property  of 
imbibing  water  and  retaining  it,  without  at  the  same  time  being 
rendered  incapable  of  permitting  liquids  to  penetrate  through  their 
pores.  A  strong  contraction  and  shrinking  of  the  surface  is  the 
general  effect  of  contact  with  these  metallic  bodies.  But  cor. 
rosive  sublimate,  and  several  of  the  salts  of  lead,  possess  a  pecu- 


INORGANIC  POISONS.  3«3 

liar  property,  in  addition  to  those  already  mentioned.  When  they 
are  present  in  excess,  they  dissolve  the  first  formed  insoluble 
compounds,  and  thus  produce  an  effect  quite  the  reverse  of  con- 
traction, namely,  a  softening  of  the  part  of  the  body  on  which 
they  have  acted. 

Salts  of  oxide  of  copper,  even  when  in  combination  with  the 
most  powerful  acids,  are  reduced  by  many  vegetable  substances, 
particularly  such  as  sugar  and  honey,  either  into  metallic  copper, 
or  into  the  red  suboxide,  neither  of  which  enters  into  combina- 
tion with  animal  matter.  It  is  well  known  that  sugar  has  been 
long  employed  as  the  most  convenient  antidote  for  pois-.-ning  by 
copper. 

With  respect  to  some  other  poisons,  namely,  hydrocyanic  acid, 
and  the  organic  bases  strychnia,  brucia,  SfC,  we  are  not  acquainted 
with  facts  calculated  to  elucidate  the  nature  of  their  action.  It 
may,  however,  be  presumed  with  much  certainty,  thai  experi- 
ments upon  their  mode  of  action  on  different  animal  sujstances 
would  very  quickly  lead  to  the  most  satisfactory  conclusions  re- 
garding the  cause  of  their  poisonous  effects. 

There  is  a  peculiar  class  of  substances,  which  are  generated 
during  certain  processes  of  decomposition,  and  which  act  upon 
the  animal  economy  as  deadly  poisons,  not  on  account  of  their 
power  of  entering  into  combination  with  it,  or  by  reason  of  theii* 
containing  a  poisonous  material,  but  -solely  by  virtue  of  their 
peculiar  condition. 

In  order  to  obtain  a  clear  conception  of  the  mode  of  action  of 
these  bodies,  it  is  necessary  to  call  to  mind  the  cause  on  which 
we  have  shown  the  phenomena  of  fermentation,  de^ay,  and 
putrefaction  to  depend. 

This  cause  may  be  expressed  by  the  following  law,  Lng  since 
proposed  by  La  Place  and  Berthollet,  although  its  tiUth  with 
respect  to  chemical  phenomena  hag  only  lately  been  proved.     "  A 

MOLECULE  SET  IN  MOTION  BY  ANY  POWER  CAN  IMPART  ITS  OWN 
MOTION  TO  ANOTHER  MOLECULE  WITH  WHICH  IT  MAY  BE  IN 
CONTACT." 

This  is  a  law  of  dynamics,  the  operation  of  which  is  manifest 
in  all  cases,  in  which  the  resistance  {force,  ajjiinity,  or  cohesion) 
opposed  to  the  motion  is  not  sufficient  to  overcome  it. 


?64  POISONS,  CONTAGIONS,  MIASMS. 

We  have  seen  that  ferment  or  yeast  is  a  body  in  the  state  of 
•Jeconi position,  the  atoms  of  which,  consequently,  are  in  a  state 
of  motion  or  transposition.  Yeast  placed  in  contiact  with  sugar 
communicates  to  the  elements  of  that  compound  the  same  state, 
in  consequence  of  which,  the  constituents  of  the  sugar  arrange 
themselves  into  new  and  simpler  forms,  namely,  into  alcohol  and 
carbonic  acid.  In  these  new  compounds  the  elements  are  united 
together  by  stronger  affinities  than  they  were  in  the  sugar,  and 
therefore  under  the  conditions  in  which  they  were  produced 
further  decomposition  is  arrested. 

We  know,  also,  that  the  elements  of  sugar  assume  totally  dit- 
ferent  arrangements,  when  the  substances  which  excite  their 
transposition  are  in  a  different  state  of  decomposition  from  the 
yeast  just  mentioned.  Thus,  when  sugar  is  acted  on  by  rennet 
or  putrefying  vegetable  juices,  it  is  not  converted  into  alcohol 
and  carbonic  acid,  but  into  lactic  acid,  mannite,  and  gum,  or  into 
butyric  acid. 

Again,  it  has  been  shown  that  yeast  added  to  a  solution  of  pure 
sugar  gradually  disappears,  but  that,  when  added  to  vegetable 
juices  which  contain  gluten  as  well  as  sugar,  it  is  reproduced 
by  the  decomposition  of  the  former  substance. 

The  yeast  with  which  these  liquids  are  made  to  ferment,  has 
itself  been  originally  produced  from  gluten. 

The  conversion  of  gluten  into  yeast  in  these  vegetable  juices 
is  dependent  on  the  decomposition  (fermentation)  of  sugar  ;  for, 
when  the  sugar  has  completely  disappeared,  any  gluten  still 
remaining  in  the  liquid  does  not  suffer  change  from  contact  with 
the  newly-deposited  yeast,  but  retains  all  the  characters  of 
gluten. 

Yeast  is  a  product  of  the  decomposition  of  gluten  ;  but  it 
readily  passes  into  v,  second  stage  of  decomposition  when  in  con- 
tact with  water.  On  account  of  its  being  in  this  state  of  further 
change,  yeast  excites  fermentation  in  a  fresh  solution  of  sugar ; 
and  if  this  second  saccharine  fluid  should  contain  gluten  (should 
it  be  wort,  for  example),  yeast  is  again  generated,  in  consequence 
of  the  transposition  of  the  elements  of  the  sugar  exciting  a 
siniilar  change  in  this  gluten. 


PUTRID  POISONS.  36« 


.,*    After  this  explanation,  the  idea  that  yeast  reproduces  itself,  as 
■eeds  reproduce  seeds,  cannot  for  a  moment  be  entertained. 

From  the  foregoing  facts  it  follows,  that  a  body  in  the  act  of  de- 
composition (it  may  be  named  the  exciter),  added  to  a  mixed  fluid 
in  which  its  constituents  are  contained,  can  reproduce  itself  in  thai 
fluid,  exactly  in  the  same  manner  as  new  yeast  is  produced 
when  yeast  is  added  to  saccharine  liquids  containing  gluten. 
This  must  be  more  certainly  effected  when  the  liquid  acted  upon 
contains  the  body  by  the  metamorphosis  of  which  the  exciter  has 
been  originally  formed. 

It  is  also  obvious  that  if  the  exciter  be  able  to  impart  its  own 
state  of  transformation  to  one  only  of  the  component  parts  of  the 
mixed  liquid  acted  upon,  its  own  reproduction  may  be  the  conse- 
quence of  the  decomposition  of  this  one  body. 

This  law  may  be  applied  to  organic  substances  forming  part 
of  the  animal  organism.  We  know  that  all  the  constituents  of 
these  substances  are  formed  from  the  blood,  and  that  the  blood 
by  its  nature  and  constitution  is  the  most  complex  of  all  existing 
matters. 

Nature  has  adapted  the  blood  for  the  reproduction  of  every 
individual  part  of  the  organism  ;  its  principal  character  consists 
in  its  component  parts  being  subordinate  to  every  attraction. 
These  are  in  a  perpetual  state  of  change  or  transformation,  which 
is  effected  in  the  most  various  ways  through  the  influence  of  the 
different  organs. 

The  blood  does  not  possess  the  power  of  causing  transforma- 
tions ;  on  the  contrary,  its  principal  character  consists  in  its  readily 
suffering  transformations ;  and  no  other  matter  can  be  compared 
with  it  in  this  respect. 

Now  it  is  a  well  known  fact,  that  when  blood,  cerebral  sub- 
stance, gall,  pus,  and  other  substances  in  a  state  of  putrefaction, 
are  laid  upon  fresh  wounds,  vomiting,  debility,  and  at  length 
death  are  occasioned.  It  is  also  well  known  that  bodies  in  ana- 
tomical rooms  frequently  pass  into  a  state  of  decomposition  ca- 
pable of  imparting  itself  to  the  living  body,  the  smallest  cut  with 
a  knife  which  has  been  used  in  their  dissection  producing  in  these 
cases  dangerous  consequences. 

The  poison  of  bad  sausages  belongs  to  this  class  of  noxioua 


366  POISONS,  CONTAGIONS,  MIASMS. 

substances.  Several  hundred  cases  are  known  in  which  death 
has  occurred  from  the  use  of  this  kind  of  food.  In  Wurtemburg 
especially  tliese  cases  are  very  frequent,  for  there  the  sausages 
are  prepared  from  very  various  materials.  Blood,  liver,  bacon, 
brains,  milk,  flour,  and  bread,  are  mixed  together  with  salt  and 
spices ;  the  mixture  is  then  put  into  bladders  or  intestines,  and 
after  being  boiled  is  smoked. 

When  these  sausages  are  well  prepared,  they  may  be  preserved 
for  months,  and  furnish  a  nourishing  savory  food  ;  but  when 
the  spices  and  salt  are  deficient,  and  particularly  when  they  are 
smoked  too  late  or  not  sufficiently,  they  undergo  a  peculiar  kind 
of  putrefaction  which  begins  at  the  centre  of  the  sausage. 
Without  any  appreciable  escape  of  gas  taking  place  they  become 
paler  in  color,  and  more  soft  and  greasy  in  those  parts  which 
have  undergone  putrefaction,  and  they  are  found  to  contain  free 
lactic  acid,  or  lactate  of  ammonia ;  products  seldom  absent  from 
putrefying  bodies,  especially  vegetable  matter. 

The  cause  of  the  poisonous  nature  of  these  sausages  was  as- 
cribed at  first  to  hydrocyanic  acid,  and  afterwards  to  sebacic  acid, 
although  neither  of  these  substances  had  been  detected  in  them. 
But  sebacic  acid  is  no  more  poisonous  than  benzoic  acid,  with 
which  it  has  so  many  properties  in  common ;  and  the  symptoms 
produced  are  sufficient  to  show  that  hydrocyanic  acid  is  not  the 
poison. 

The  death  which  is  the  consequence  of  poisoning  by  putrefied 
sausages  succeeds  very  lingering  and  remarkable  symptoms. 
There  is  a  gradual  wasting  of  muscular  fibre,  and  of  all  the  con- 
stituents of  the  body  similarly  composed ;  the  patient  becomes 
much  emaciated,  dries  to  a  complete  mummy,  and  finally  dies. 
The  carcase  is  stiff  as  if  frozen,  and  is  not  subject  to  putrefac- 
tion. During  the  progress  of  the  disease  the  saliva  becomes 
viscous,  and  acquires  an  offensive  smell. 

Experiments  have  been  made  for  the  purpose  of  ascertaining 
the  presence  of  some  matter  in  the  sausages,  to  which  their 
poisonous  action  could  be  ascribed  ;  but  no  such  matter  has  been 
detected.  Boiling  water  and  alcohol  completely  destroy  the 
poisonous  properties  of  the  sausages,  without  themselves  acquiring 
«imilar  properties. 


PUTRID  POISONS.  3«7 


Now  this  is  the  peculiar  character  of  all  substances  which 
exert  an  action  by  virtue  of  their  existing  condition — of  those 
bodies  the  elements  of  which  are  in  a  state  of  decomposition  or 
transposition  ;  a  state  which  is  destroyed  by  boiling  water  and 
alcohol  without  the  cause  of  the  influence  being  imparted  to  those 
liquids :  for  a  state  of  action  or  power  cannot  be  preserved  in  a 
liquid. 

Sausages,  in  the  state  here  described,  exercise  an  action  upon 
the  organism,  in  consequence  of  the  stomach  and  other  parts 
with  which  they  come  in  contact  not  having  the  power  to  arrest 
their  decomposition ;  and  entering  the  blood  in  some  way  or 
other,  while  still  possessing  their  whole  power,  they  impart  their 
peculiar  action  to  the  constituents  of  that  fluid. 

The  poisonous  properties  of  decayed  sausages  are  not  destroy- 
ed by  the  stomach  as  those  of  the  small-pox  virus  are.  All  the 
substances  in  the  body  capable  of  putrefaction  are  gradually 
decomposed  during  the  course  of  the  disease,  and  after  death 
nothing  remains,  except  fat,  tendons,  bones,  and  a  few  other  sub- 
stances incapable  of  putrefying  in  the  conditions  afforded  by  the 
body.* 


*  In  a  case  of  poisoning  by  sausages,  which  was  communicated  to  me  by 
Herr  Salzer,  and  which  occurred  r  Sausenbach,  near  Schwab isch hall,  in 
May,  1842,  of  all  the  remedies  that  were  tried  sulphuretted  hydrogen 
water  was  found  to  possess  very  peculiar  efficacy.  All  the  poisoned  indi- 
viduals in  whom  it  was  tried  early  enough  were  saved.  In  those  affected 
by  the  poison  there  appeared  hoarseness  and  dryness  in  the  throat,  and  a 
universal  feeling  of  dryness,  constipation  without  swelling  of  the  abdomeri, 
and  without  perceptible  difficulty  of  breathing ;  faintness ;  dilated  pupil 
with  impaired  vision  ;  perfect  consciousness  and  unimpaired  motion  of  all 
the  muscles,  except  those  supplied  with  nerves  from  the  sympathetic  sys- 
tem, and  rapid  putrescence  of  the  dead  bodies.  The  effects  were  not  only 
dependent  on  the  amount  of  poisoned  sausage  taken,  but  also  very  peculiar 
in  each  case  ;  and  in  one  case  there  was  actually  no  effect,  where  a  large 
quantity  of  the  same  sausages  had  been  consumed.  In  the  treatment,  the 
sulphuretted  hydrogen  water  decidedly  checked  the  poisonous  action  :  the 
patients  first  perceived  greater  ease  in  swallowing ;  then  the  general 
tension  and  dryness  diminished;  the  voice,  which  had  been  lost,  returned; 
the  skin  became  moister,  the  countenance  lighter,  and  the  pressure  on  the 
eye  was  relieved. 

Ammonia,  diluted  so  as  to  be  taken  as  a  drink,  and  at  the  same  time 


368  POISONS,  CONTAGIONS,  MIASMS. 


It  is  impossible  to  mistake  the  modus  operandi  oi  this  poiaon, 
for  Colin  has  clearly  proved  that  muscle,  urine,  cheese,  cerebral 
substance,  and  other  matters,  in  a  state  of  putrefaction,  commu- 
nicate their  own  state  of  decomposition  to  substances  much 
less  prone  to  change  of  composition  than  the  blood.  When 
placed  in  contact  with  a  solution  of  sugar,  they  cause  its  putre- 
faction, or  the  transposition  of  its  elements  into  carbonic  acid  and 
alcohol. 

When  putrefying  muscle  or  pus  is  placed  upon  a  fresh  wound 
it  occasions  disease  and  death.  It  is  obvious  that  these  substances 
communicate  their  own  state  of  putrefaction  to  the  sound  blood 
FROM  WHICH  THEY  WERE  PRODUCED,  exactly  in  the  same  manner 
as  gluten  in  a  state  of  decay  or  putrefaction  causes  a  similar 
transformation  in  a  solution  of  sugar. 

Poisons  of  this  kind  are  even  generated  by  the  body  itself  in 
particular  diseases.  In  small-pox,  plague,  and  syphilis,  substances 
of  a  peculiar  nature  are  formed  from  the  constituents  of  the 
blood.  These  matters  are  capable  of  inducing  in  the  blood  of  a 
healthy  individual  a  decomposition  similar  to  that  of  which  they 
themselves  are  the  subjects  ;  in  other  words,  they  produce  the 
same  disease.  The  morbid  virus  appears  to  reproduce  itself  just 
as  seeds  appear  to  reproduce  seeds. 

The  mode  of  action  of  a  morbid  virus  exhibits  such  a  strong 
similarity  to  the  action  of  yeast  upon  liquids  containing  sugar, 
and  gluten,  that  the  two  processes  have  been  long  since  compared 
to  one  another,  although  merely  for  the  purpose  of  illustration. 
But  when  the  phenomena  attending  the  action  of  each  respective- 
ly are  considered  more  closely,  it  will  in  reality  be  seen  that 
their  influence  depends  upon  the  same  cause. 

In  dry  air,  and  in  the  absence  of  moisture,  all  these  poisons 
remain  for  a  long  time  unchanged  ;  but  when  exposed  to  the  air 
in  the  moist  condition,  they  lose  very  rapidly  their  peculiar  pro^ 
perties.     In  the  former  case,  those  conditions   \re  afforded  which 

rubbed  into  the  skin,  afforded  relief;  but  this  was  only  temporary,  and 
there  was  no  improvement  observed  oa  continuing  this  treatment. 

Chlorine  diluted  with  water,  and  used  externally  and  internally,  produced 
no  improvement :  on  the  contrary,  the  tension  and  dryness  were  increased 
so  that  it  soon  became  necessary  to  relinquish  this  treatment. 


MORBID  POISONS.  36d 


arrest  their  decomposition  without  destroying  it ;  in  the  latter,  all 
tile  circumstances  necessary  for  the  completioij  of  their  deoom< 
position  are  presented. 

The  temperature  at  which  water  boils,  and  contact  with  alcohol, 
render  such  poisons  inert.  Acids,  salts  of  mercury,  sulphurous 
acid,  chlorine,  iodine,  bromine,  aromatic  substances,  volatile  oils, 
and  particularly  empyreumatic  oils,  smoke,  and  a  decoction  of 
eoffee,  completely  destroy  their  contagious  properties,  in  some 
cases  combining  with  them  or  otherwise  effecting  their  decompo- 
sition. Now  all  these  agents,  without  exception,  retard  ferment- 
ation, putrefaction,  and  decay,  and  when  present  in  sufficient 
quantity,  completely  arrest  these  processes  of  decomposition. 

A  peculiar  matter  to  which  the  poisonous  action  is  duo,  cannot, 
we  have  seen,  be  extracted  from  decayed  sausages ;  and  it  is 
equally  impossible  to  obtain  such  a  principle  from  the  virus  of 
small-pox  or  plague,  and  for  this  reason,  that  their  peculiar 
power  is  due  to  an  active  condition,  only  recognisable  by  our 
senses  through  the  phenomena  which  it  produces. 

In  order  to  explain  the  effects  of  contagious  matters,  a  peculiar 
principle  of  life  has  been  ascribed  to  them — a  life  similar  to 
that  possessed  by  the  germ  of  a  seed,  which  enables  it  under 
favorable  conditions  to  develope  and  multiply  itself.  There  cannot 
be  a  more  inaccurate  image  of  these  phenomena  ;  it  is  one 
which  is  applicable  to  contagions,  as  well  as  to  ferment,  to  animal 
and  vegetable  substances  in  a  state  of  fermentation,  putrefaction, 
or  decay,  and  even  to  a  piece  of  decaying  wood,  which  by  mere 
contact  with  fresh  wood,  causes  the*  latter  to  undergo  gradually 
the  same  changes,  and  become  decayed  and  mouldered, 
^v.  If  the  property  possessed  by  a  body  of  producing  such  a  change 
in  any  other  substance  as  causes  the  reproduction  of  itself,  witii 
all  its  properties,  be  regarded  as  life,  then,  indeed,  all  the  above 
phenomena  must  be  ascribed  to  life.  But  in  that  case  they  must 
not  be  considered  as  the  only  processes  due  to  vitality,  for  the 
aho\e  interpretation  of  the  expression  embraces  the  majority  of 
the  phenomena  which  occur  in  organic  chemistry.  Life  would, 
accoi'ding  to  that  view,  be  admitted  to  exist  in  every  body  in 
which  chemical  forces  act. 

If  a  body  A,  for  example  oxamide  (a  substance  scarcely  solu- 
17* 


3t0  POISONS,  CONTAGIONS,  MIASMS. 


ble  in  water,  and  without  the  slightest  taste),  be  brought  into 
contact  with  another  comiiound  B,  which  is  to  be  reproduced ; 
and  if  this  second  body  be  oxalic  acid  dissolved  in  water,  then 
the  following  changes  are  observed  to  take  place : — the  oxamide 
is  decomposed  by  the  oxalic  acid,  provided  the  conditions  neces- 
sary for  their  exercising  an  action  upon  one  another  are  present. 
The  elements  of  water  unite  with  the  constituents  of  oxamide, 
and  AMMONIA  is  one  product  formed,  and  oxalic  acid  the  other, 
both  in  exactly  the  proper  proportions  to  combine  and  form  a 
neutral  salt. 

Here  the  contact  of  oxamide  and  oxalic  acid  induces  a  trans- 
formation of  the  oxamide,  which  is  decomposed  into  oxalic  acid 
and  ammonia.  The  oxalic  acid  thus  formed,  as  well  as  that 
originally  added,  are  neutralized  by  the  ammonia — as  far  as  that 
product  suffices  to  neutralize  them  ;  but,  of  course^  as  much  free 
oxalic  acid  exists  after  the  decomposition  as  before  it,  and  is  still 
possessed  of  its  original  power.  It  matters  not  whether  the  free 
oxalic  acid  is  that  originally  added,  or  that  newly  produced  ;  it 
is  certain  that  it  has  been  reproduced  in  an  equal  quantity  by 
the  decomposition. 

If  we  now  add  to  the  same  mixture  a  fresh  portion  of  oxamide, 
exactly  equal  in  quantity  to  that  first  used,  and  treat  it  in  the 
same  manner,  the  same  decomposition  is  repeated  ;  the  free  oxalic 
acid  enters  into  combination  whilst  another  portion  is  liberated. 
In  this  manner  a  very  minute  quantity  of  oxalic  acid  may  be 
made  to  effect  the  decomposition  of  several  hundred  pounds  of 
oxamide  ;  and  one  grain  of  the  acid  to  reproduce  itself  in  un- 
limited quantity. 

We  know  that  the  contact  of  the  virus  of  small-pox  causes 
such  a  change  in  the  blood,  as  gives  rise  to  the  reproduction  of 
the  poison  from  the  constituents  of  the  fluid.  This  transforma- 
tion is  not  arrested  until  all  the  particles  of  the  blood  susceptible 
of  the  decomposition  have  undergone  the  metamorphosis.  We 
have  just  seen  that  the  contact  of  oxalic  acid  with  oxamide  caused 
the  production  of  fresh  oxalic  acid,  which  in  its  turn  exercised 
the  same  action  on  a  new  portion  of  oxamide.  The  transforma- 
tion was  only  arrested  in  consequence  of  the  quantity  of  oxamide 
present  bsin  r  limit-^rl.     In  their  form  both  these  transformationa 


MORBID  POISONS.  871 


belong  to  the  same  class ;  but  although  what  heie  takes  place 
exactly  corresponds  to  the  definition  of  life  above  assumed,  no 
unprejudiced  mind  would  admit  vitality  in  either  process ;  since 
they  are  obviously  chemical  processes  dependent  upon  the  com- 
mon chemical  forces. 

The  best  "definition  of  life  involves  something  more  than  mere 
reproduction,  namely,  the  idea  of  an  active  power  exercised  by 
VIRTUE  OF  A  DEFINITE  FORM,  and  production  and  generation  in  a 
DEFINITE  form.  By  chemical  agency  we  shall  some  day  be  able 
to  produce  the  constituents  of  muscular  fibre,  skin,  and  hair  ;  but 
we  cannot  form  by  their  means  an  organized  tissue,  or  an  or- 
ganic cell. 

The  production  of  organs,  the  co-operation  of  a  system  of  or- 
gans, and  their  power  not  only  to  produce  their  component  parts 
from  the  food  presented  to  them,  but  to  generate  themselves  in  their 
original  form  and  with  all  their  properties,  are  characters  be- 
longing exclusively  to  organic  life,  and  constitute  a  form  of 
reproduction  independent  of  chemical  powers. 

The  chemical  forces  are  subject  to  the  invisible  cause  by 
which  this  form  is  produced.  Of  the  existence  of  this  cause 
itself  we  are  made  aware  only  by  the  phenomena  which  it  pro- 
duces. Its  laws  must  be  investigated  just  as  we  investigate 
those  of  the  other  powers  which  effect  motion  and  changes  in 
matter. 

The  chemical  forces  are  subordinate  to  this  cause  of  life,  just 
as  they  are  to  electricity,  heat,  mechanical  motion,  and  friction. 
By  the  influence  of  the  latter  forces,  they  suffer  changes  in  their 
direction,  an  increase  or  diminution  of  their  intensity,  or  a  com- 
plete cessation  or  reversal  of  their  action. 

Such  an  influence  and  no  other  is  exercised  by  the  vital  prin- 
ciple over  the  chemical  forces  ;  but  in  every  case  where  com- 
bination or  decomposition  takes  place,  chemical  affinity  and 
cohesion  are  in  action. 

The  vital  principle  is  only  known  to  us  through  the  peculiar 
form  of  its  instruments,  that  is,  through  the  organs  in  which  it 
resides.  Hence,  whatever  kind  of  energy  a  substance  may 
possess,  if  it  is  amorphous  and  destitute  of  organs  from  which  the 
impulse  of  motion  or  .change  proceeds,  it  does  not  live.      Its 


572  POISONS,  CONTAGIONS,  MIASMS. 

energy  depends  in  this  case  on  a  chemical  action.  Light,  heat, 
electricity,  or  other  influences,  may  increase,  diminish,  or  arrest 
this  action,  but  they  are  not  its  efficient  cause. 

In  this  way  the  vital  principle  governs  the  chemical  powers  in 
the  living  body,  and  this  is  particularly  apparent  with  regard  to 
vegetable  life.  All  those  substances  to  whicli  we  apply  the 
general  name  of  food,  and  all  the  bodies  formed  from  them  in  the 
organism,  are  chemical  compounds.  The  vital  principle  has, 
therefore,  no  other  resistance  to  overcome,  in  order  to  convert 
these  substances  into  component  parts  of  the  organism,  than  the 
chemical  powers  by  which  their  constituents  are  held  together. 
If  the  food  possessed  life,  not  merely  the  chemical  forces,  but  this 
vitality,  would  offer  resistance  to  the  vital  force  of  the  organism 
it  nourished. 

The  equilibrium  in  the  chemical  attractions  of  the  constituents 
of  the  food  is  disturbed  by  the  vital  principle  of  the  plant,  as  we 
know  it  may  be  by  many  other  causes.  But  the  union  of  its  ele- 
ments, so  as  to  produce  new  combinations  and  forms,  indicates 
the  presence  of  a  peculiar  mode  of  attraction,  and  the  existence 
of  a  power  distinct  from  all  other  powers  of  nature,  namely,  the 
vita!  principle. 

The  vital  principle  opposes  to  the  continual  action  of  the 
atmospheric  moisture  and  temperature  upon  the  organism,  a  re- 
sistance which  is,  up  to  a  certain  point,  invincible.  It  is  by  the 
constant  neutralization  and  renewal  of  these  external  influences 
that  life  and  motion  are  maintained. 

The  greatest  wonder  in  the  living  organism  is  the  fact  that  an 
unfathomable  Wisdom  has  made  the  cause  of  a  continual  decom- 
position or  destruction,  namely,  the  support  of  the  process  of  re- 
spiration, to  be  the  means  of  renewing  the  organism,  and  of 
resisting  all  the  other  atn^.ospheric  influences,  such  as  those  of 
moisture  and  changes  of  temperature. 

When  a  chemical  compound  of  simple  constitution  is  introduced 
into  the  stomach,  or  any  other  part  of  the  organism,  it  must  ex- 
ercise a  chemical  action  upon  all  substances  with  which  it  comes 
in  contact ;  for  we  know  the  peculiar  character  of  such  a  body 
to  be  an  aptitude  and  power  to  enter  into  combinations  and  effect 
decompositions. 


THEIR  MODE  OF  ACTION.  ^ 

'The  chemical  action  of  such  a  compound  is,  of  course,  opposed 
by  the  vital  principle.  The  results  produced  depend  upon  the 
strength  of  their  respective  actions ;  either  an  equilibrium  of  both 
powers  is  attained,  a  change  being  effected  without  the  destruction 
of  the  vital  principle,  in  which  case  A  medicinal  effect  is  occa- 
sioned ;  or  the  acting  body  yields  to  the  superior  force  of  vitality, 
that  is,  IT  IS  DIGESTED ;  or,  lastly,  the  chemical  action  obtains  the 
ascendency,  and  it  acts  as  a  poison. 

Every  substance  may  be  considered  as  nutriment  which  loses 
its  former  properties  when  acted  on  by  the  vital  principle,  and 
does  not  exercise  a  chemical  action  upon  the  living  organ. 

Another  class  of  bodies  change  the  direction,  the  strength, 
and  intensity  of  the  resisting  force  (the  vital  principle),  and 
thus  exert  a  modifying  influence  upon  the  functions  of  its  or- 
gans. They  produce  a  disturbance  in  the  system,  either  by 
their  presence,  or  by  themselves  undergoing  a  change  ;  these  are 

MEDICAMENTS. 

A  third  class  of  compounds  are  called  poisons,  when  they  pos- 
sess t  lie  property  of  uniting  with  organs  or  with  their  component 
parts,  and  when  their  power  of  effecting  this  is  stronger  than  the 
resistance  offered  by  the  vital  principle. 

The  quantity  of  a  substance  and  its  condition  must  obviously 
completely  change  the  mode  of  its  chemical  action. 

Increase  of  quantity  is  known  to  be  equivalent  to  superior 
affinity.  Hence  a  medicament  administered  in  excessive  quan- 
tity may  act  as  a  poison,  and  a  poison  in  small  doses  as  a 
medicament. 

Food  will  act  as  a  poison,  that  is,  it  will  produce  disease,  when 
it  is  able  to  exercise  a  chemical  action  by  virtue  of  its  quantity  ; 
or  when  either  its  condition  or  its  presence  retards,  prevents,  or 
arrests  the  motion  of  any  organ. 

A  compound  acts  as  a  poison  when  all  the  parts  of  an  organ 
with  which  it  is  brought  into  contact  enter  into  chemical  combi- 
nation with  it,  while  it  may  operate  as  a  medicine  when  it  pro- 
duces only  a  partial  change. 

No  other  component  part  of  the  organism  can  be  compared  to 
the  blood,  in  respect  of  the  feeble  resistance  which  it  offers  to 
exterior  influences.     The  blood  is  not  an  organ  which  is  formed, 


«74  POISONS,  CONTAGIONS,  MIASMS. 

but  an  organ  in  the  act  of  formation  ;  indeed,  it  is  the  sum  of  all 
the  organs  which  are  being  formed.  The  chemical  force  and  the 
vital  principle  hold  each  other  in  such  perfect  equilibrium,  that 
every  disturbance,  however  trifling,  or  from  whatever  cause  it 
may  proceed,  effects  a  change  in  the  blood.  This  liquid  possesses 
so  little  of  permanence  that  it  cannot  be  removed  from  the  body 
without  immediately  suffering  a  change,  and  cannot  come  in 
contact  with  any  organ  in  the  body,  ■  without  yielding  to  its 
attraction. 

The  slightest  action  of  a  chemical  agent  upon  the  blood  ex- 
ercises an  injurious  influence  ;  even  the  momentary  contact  with 
the  air  in  the  lungs,  although  effected  through  the  medium  of 
cells  and  membranes,  alters  the  color  and  other  qualities  of  the 
blood.  Every  chemical  action  propagates  itself  through  the  mass 
of  the  blood  ;  for  example,  the  active  chemical  condition  of  the 
constituents  of  a  body  undergoing  decomposition,  fermentation, 
putrefaction,  or  decay,  disturbs  the  equilibrium  between  the 
chemical  force  and  the  vital  principle  in  the  circulating  fluid,  and 
overcomes  the  latter.  Numerous  modifications  in  the  composition 
and  condition  of  the  compounds  produced  from  the  elements  of 
the  blood,  result  from  the  conflict  of  the  vital  force  with 
chemical  affinity,  in  their  incessant  endeavor  to  overcome  one 
another. 

All  the  characters  of  the  phenomena  of  contagion  tend  to  dis- 
prove the  existence  of  vitality  in  contagious  matters.  They 
without  doubt  exercise  an  influence  very  similar  to  some  pro- 
cesses in  the  living  organism  ;  but  the  cause  of  this  influence  is 
chemical  action,  which  is  capable  of  being  subdued  by  other 
chemical  actions,  by  opposed  agencies. 

Several  of  the  poisons  generated  in  the  body  by  disease  lose  all 
their  power  when  introduced  into  the  stomach,  but  others  are  not 
thus  destroyed. 

It  is  a  fact  very  decisive  of  their  chemical  nature  and  mode 
of  action,  that  those  poisons  which  are  neutral  or  alkaline,  such 
as  the  poisonous  matter  of  the  contagious  fever  in  cattle  {typhiLS 
aonfagiosus  ruminantium),  or  that  of  the  small-pox,  lose  their 
whole  power  of  contagion  in  the  stomach  ;  whilst  that  of  sausa- 


THEIR  MODE  OF  ACTION.  375 

ges,  which  has  an  acid  reaction,  retains  all  its  frightful  properties 
under  the  same  circumstances. 

In  the  former  of  these  cases,  the  free  acid  present  in  the 
stomach  destroys  the  action  of  the  poison,  the  chemical  properties 
oii  which  are  opposed  to  it  ;  Miiilst  in  the  latter  it  strengthens,  or 
at  all  events  does  not  offer  any  impediment  to  poisonous  action. 

Microscopical  examination  hias  detected  peculiar  bodies  resem- 
bling the  globules  of  the  blood  in  malignant  putrefying  pus,  in 
the  matter  of  vaccine,  &c.  The  presence  of  these  bodies  has 
given  weight  to  the  opinion,  that  contagion  proceeds  from  the 
development  of  a  diseased  organic  life  ;  and  these  formations 
have  been  regarded  as  the  living  seeds  of  disease. 

This  view,  which  does  not  admit  of  discussion,  has  led  those 
philosophers  who  are  accustomed  to  search  for  explanations  of 
phenomena  in  forms,  to  consider  the  yeast  produced  by  the  fer- 
mentation of  beer  as  possessed  of  life.  They  have  imagined  it 
to  be  composed  of  animals  or  plants,  which  nourish  themselves 
from  the  sugar  in  which  they  are  placed,  and  at  the  same  time 
yield  alcohol  and  carbonic  acid  as  excrementitious  matters.* 

It  would  perhaps  appear  wonderful  if  bodies,  possessing  a 
crystalline  structure  and  geometrical  figure,  were  formed  during 
the  processes  of  fermentation  and  putrefaction  from  the  organic 
substances  and  tissues  of  organs.  We  know,  on  the  contraiy, 
that  the  complete  dissolution  into  organic  compounds  is  preceded 
by  a  series  of  transformations,  in  which  the  organic  structures 
gradually  resign  their  forms. 

Blood,  in  a  state  of  decomposition,  may  appear  to  tho  eye  un- 
changed ;  and  when  we  recognise  the  globules  of  blood  in  a 
liquid  contagious  matter,  the  utmost  that  we  can  thence  infer  is, 
that  those  globules  have  taken  no  part  in  the  process  of  decom- 
position. All  the  phosphate  of  lime  may  be  removed  from  bones, 
leaving  them  transparent  and  flexible  like  leatliea*,  without  the 
form  of  the  bones  being  in  the  smallest  degree  lost.  Again  : 
bones  may  be  burned  until  they  be  quite  white,  and  consist 
merely  of  a  skeleton  of  phosphate  of  lime,  but  they  will  still 
possess  their  original  form.     In  the  same  way  processes  of  de- 

*  Annalen  der  Pharmacie,  Band  xxix.,  S.  93  und  100. 


376  POISONS,  CONTAGIONS,  MIASMS. 

composition  in  the  blood  niay  affect  individual  constituents  only 
of  that  fluid,  which  will  become  destroyed  and  disappear,  whilst 
113  other  parts  will  maintain  the  original  form. 

Several  kinds  of  contagion  are  propagated  through  the  air  :  so 
that  according  to  the  view  already  mentioned,  we  must  ascribe 
life  to  a  gas,  that  is,  to  an  aeriform  body. 

All  the  supposed  proofs  of, the  vitality  of  contagions  are 
merely  ideas  and  figurative  representations,  fitted  to  render  the 
phenomena  more  easy  of  apprehension  by  our  senses,  without 
explaining  them.  These  figurative  expressions,  with  which  we 
are  so  willingly  and  easily  satisfied  in  all  sciences,  are  the  foes 
of  all  inquiries  into  the  mysteries  of  /lature  ;  they  are  like  the 
fata  jnorgajm,  which  show  us  deceitful  views  of  seas,  fertile  fields, 
and  luscious  fruits,  but  leave  us  languishing  when  we  have  most 
need  of  what  they  promise. 

It  is  certain  that  the  action  of  contagions  is  the  result  of  a  pe- 
culiar influence  dependent  on  chemical  forces,  and  in  no  way 
connected  with  the  vital  principle.  This  influence  is  destroyed 
by  chemical  actions,  and  manifests  itself  wherever  it  is  not  sub- 
dued by  some  antagonist  power.  Its  existence  is  recognised  in  a 
connected  series  of  changes  and  transformations,  in  which  it 
causes  all  substances  capable  of  undergoing  similar  changes  to 
participate. 

An  animal  substance  in  the  act  of  decomposition,  or  a  sub- 
stance generated  from  the  component  parts  of  a  living  body  by 
disease,  communicates  its  own  condition  to  all  parts  of  the  system 
capable  of  entering  into  the  same  state,  if  no  cause  exist  in 
these  parts  by  which  the  change  is  counteracted  or  destroyed. 

Disease  is  thus  excited  by  contagion. 

The  transformations  produced  by  the  disease  assume  a  series 
of  forms. 

In  order  to  obtain  a  clear  conception  of  these  transformations, 
we  may  consider  the  changes  which  substances,  more  simply 
composed  than  the  living  body,  suffer  from  the  influence  of  simi- 
lar causes.  When  putrefying  blood  or  yeast  in  the  act  of  trans- 
foimation  is  placed  in  contact  with  a  solution  of  sugar,  the  ele- 
ments of  the  latter  substance  are  transposed,  so  as  to  form  alcohol 
and  carbonic  acid. 


THEIR  MODE  OF  ACTION.  .^-^V 

A  piece  of  the  rennet-stomach  of  a  calf  in  a  state  of  decomjK)- 
sition  occasions  the  elements  of  sugar  to  assume  a  different 
arrangement.  The  sugar  is  converted  mto  lactic  acid  without 
the  addition  or  loss  of  any  element.  One  atom  of  sugar  of 
grapes  Cja  H^g  Oig  yields  two  atoms  of  lactic  acid  =  2  (C, 
H.    O.  ). 

When  the  juice  of  onions  or  of  beet-root  is  made  to  ferment  at 
high  temperatures,  lactic  acid,  mannite,  and  gum  are  formed. 
Thus,  according  to  the  different  states  of  the  transposition  of  the 
elements  of  the  exciting  body,  the  elements  of  the  sugar  arrange 
themselves  in  different  manners,  that  is,  different  products  are 
formed. 

The  immediate  contact  of  the  decomposing  substance  with  the 
sugar  is  the  cause  by  which  its  particles  are  made  to  assume  new 
forms  and  natures.  The  removal  of  that  substance  occasions 
the  cessation  of  the  decomposition  of  the  sugar,  so  that  should 
its  transformation  be  completed  before  the  sugar,  the  latter  can 
suffer  no  further  change. 

In  none  of  these  processes  of  decomposition  is  tlie  exciting 
body  reproduced  ;  for  the  conditions  necessary  to  its  reproduction 
do  not  exist  in  the  elements  of  the  sugar. 

Just  as  yeast,  putrefying  flesh,  and  the  stomach  of  a  calf  in  a 
state  of  decomposition,  when  introduced  into  solutions  of  sugar, 
effect  the  transformation  of  this  substance,  without  being  them- 
selves regenerated  ;  in  the  same  manner,  miasms  and  certain 
contagious  matters  produce  diseases  in  the  human  organism,  by 
communicating  the  state  of  decomposition,  of  which  they  them- 
selves are  the  subject,  to  certain  parts  of  the  organism,  without 
themselves  being  reproduced  in  their  peculiar  form  and  nature 
during  the  pj;ogress  of  the  decomposition. 

The  disease  in  this  case  is  not  contagious. 

But,  when  yeast  is  introduced  into  a  mixed  liquid  containing 
both  sugar  and  gluten,  such  as  wort,  the  act  of  decomposition  of 
the  sugar  effects  a  change  in  the  form  and  nature  of  the  gluten, 
which  is,  in  consequence,  also  subjected  to  transformation.  As 
lon^;  as  some  of  the  fermenting  sugar  remains,  gluten  continues 
to  be  separated  as  yeast,  and  this  new  matter  in  its  turn  excites 
fermentation  in  a  fiesii  solution  of  sugar  or  \vort.     If  the  sugar, 


378  POISONS,  CONTAGIONS,  MIASMS. 


however,  should  be  first  decomposed,  the  gluten  remaining- in  so ■ 
lution  is  not  converted  into  yeast.  We  see,  therefore,  that  the 
reproduction  of  the  exciting  body  or  ferment  here  depends — 

1.  Upon  the  presence  of  that  substance  from  which  it  was 
originally  formed ; 

2.  Upon  the  presence  of  a  compound  capable  of  being  decom- 
posed by  contact  with  the  exciting  body. 

If  we  express  in  the  same  terms  the  reproduction  of  conta- 
gious matter  in  contagious  diseases,  since  it  is  quite  certain  that 
they  must  have  their  origin  in  the  blood,  we  must  admit  that  the 
blood  of  a  healthy  individual  contains  substances,  by  the  decom- 
position of  which  the  exciting  body  or  contagion  can  be  produced. 
It  must  further  be  admitted,  when  contagion  results,  that  the 
blood  contains  a  second  constituent  capable  of  being  decom- 
posed by  the  exciting  body.  It  is  only  in  consequence  of  the 
transformation  of  the  second  constituent,  that  the  original  exciting 
body  can  be  reproduced. 

A  susceptibility  of  contagion  indicates  the  presence  of  a 
certain  quantity  of  this  second  body  in  the  blood  of  a  healthy 
individual.  The  susceptibility  for  the  disease  and  its  intensity 
must  augment  according  to  the  quantity  of  that  body  present  in 
the  blood  ;  and  in  proportion  to  its  diminution  or  disappearance, 
the  course  of  the  disease  will  change. 

When  a  quantity,  however  small,  of  contagious  matter, 
that  is  of  the  exciting  body,  is  introduced  into  the  blood  of  a 
healthy  individual,  it  will  be  again  generated  in  the  blood, 
just  as  yeast  is  reproduced  from  wort.  Its  condition  of  trans- 
formation will  be  communicated  to  a  constituent  of  the  blood  ; 
and  in  consequence  of  the  transformation  suffered  by  this 
substance,  a  body  identical  with  or  similar  to  the  exciting  or 
contagious  matter  will  be  produced  from  another  constituent 
substance  of  the  blood.  The  quantity  of  the  exciting  body 
newly  produced  must  constantly  augment,  if  its  further  trans- 
formation or  decomposition  p  'oceeds  more  slowly  than  that  of 
the  compound  in  th«  blood,  the  decomposition  of  which  it 
effects. 

If  the  transformation  of  the  yeast  generated  in  the  fermen- 
tation of  wort  proceeded  with  the  same  rapidity  as  that  of  the 


THEIR  MODE  OF  ACTION.  S75 

particles  of  the  sugar  contained  in  it,  both  would  sim  il- 
taneously  disappear  when  the  fermentation  was  completed. 
But  yeast  requires  a  much  longer  time  for  decomposition 
than  sugar,  so  that  after  the  latter  has  completely  disappeared, 
there  remains  a  much  larger  quantity  of  yeast  than  existed 
in  the  fluid  at  the  commencement  of  the  fermentation, — yeast 
which  is  still  in  a  state  of  incessant  progressive  transformation, 
and  therefore  possessed  of  all  its  peculiar  properties. 

The  state  of  change  or  decomposition  which  affects  one  particle 
of  blood,  is  imparted  to  a  second,  a  third,  and  at  last  to  all  tno 
particles  of  blood  in  the  whole  body.  It  is  communicated  in 
like  manner  to  the  blood  of  another  individual,  to  that  of  a  third 
person,  and  so  on — or,  in  other  words,  the  disease  is  excited  in 
them  also. 

It  is  quite  certain  that  a  number  of  peculiar  substances 
exist  in  the  blood  of  different  men,  in  that  of  the  same 
man  at  different  periods  of  his  development,  and  in  that  of 
animals. 

The  blood  of  the  same  individual  contains,  in  childhood  and 
youth,  variable  quantities  of  substances,  which  are  absent  from 
it  in  no  other  stages  of  growth.  The  susceptibility  of  contagion 
by  peculiar  exciting  bodies  in  childhood,  indicates  a  propagation 
and  regeneration  of  the  exciting  bodies,  in  consequence  of  tho 
transformation  of  certain  substances  present  in  the  blood,  and 
in  the  absence  of  which  no  contagion  would  ensue.  The  form 
of  a  disease  is  termed  benignant,  when  the  transformations 
OF  TWO  constituents  of  the  body  not  essential  to  life,  are  simul- 
taneously completed  without  the  other  parts  taking  a  share  in 
the  decomposition  ;  it  is  termed  malignant  when  they  r\flrp«»t 
essential  organs. 

It  cannot  be  supposed  that  the  different  changes  in  the 
substance  of  the  existing  organs,  by  which  their  constituents  are 
converted  into  fat,  muscular  fibre,  substance  of  the  brain  and 
nerves,  bones,  hair,  &;c.,  and  the  transformation  of  food  into 
blood,  can  take  place  without  the  simultaneous  formation  of  new 
compounds  which  require  to  be  removed  from  the  body  by  the 
organs  of  excretion. 

In  an  adult  these  excretions  do  not  vary  much  either  in  Utcir 


380  POISONS,  CONTAGIONS,  MIASMS. 

nature  or  quantity.  The  food  taken  is  not  employed  in  increas- 
ing the  size  of  the  body,  but  merely  for  the  purpose  of  replacing 
any  substances  which  may  be  consumed  by  the  various  actions 
in  the  organism  ;  every  motion,  every  manifestation  of  organic 
properties,  and  every  organic  action  being  attended  by  a  change 
in  the  material  of  the  body,  and  by  the  assumption  of  a  new  form 
by  its  constituents.* 

But  in  a  child  this  normal  condition  of  sustenance  is  accom- 
panied by  an  abnormal  condition  of  growth,  and  increase  in  the 
size  of  the  body,  and  of  each  individual  part  of  it.  Hence, 
there  must  be  a  much  larger  quantity  of  foreign  substances,  not 
belonging  to  the  organism,  ditfused  through  every  part  of  the 
blood  in  the  body  of  a  young  individual. 

When  the  organs  of  secretion  are  in  proper  action,  these 
..ubstances  will  be  removed  from  the  system ;  but  when  the 
functions  of  those  organs  are  impeded,  they  will  remain  in 
the  blood,  or  become  accumulated  in  particular  parts  of  the 
body.  The  skin,  lungs,  and  other  organs,  assume  the  functions 
of  the  diseased  secreting  organs,  and  the  accumulated  substances 
are  eliminated  by  them.  If,  when  thus  exhaled,  these  sub- 
stances happen  to  be  in  the  state  of  progressive  transformation, 
they  are  contagious  ;  that  is,  they  are  able  to  produce  the 
same  state  of  disease  in  another  healthy  organism,  provided  the 
latter  organism  is  susceptible  of  their  action — or,  in  other  words, 
contains  a  matter  capable  of  suffering  the  same  process  of 
decomposition. 

The  production  of  matters  of  this  kind,  which  render  the  body 
susceptible  of  contagion,  may  be  occasioned  by  the  manner  of 
living,  or  by  the  nutriment  taken  by  an  individual.  A  super- 
abundance of  strong  and  otherwise  wholesome  food  may  produce 
them,  as  well  as  a  deficiency  of  nutriment,  uncleanliness,  or 
even  the  use  of  decayed  substances  as  food. 

*  The  experiments  of  Barruel  upon  the  different  odors  emitted  from 
blood  on  the  addition  of  sulphuric  acid,  prove  that  peculiar  substances  are 
contained  in  the  blood  of  different  individuals  ;  the  blood  of  a  man  of  a  fair 
complexion  and  that  of  a  man  of  dai-k  complexion  were  found  to  yield  dif- 
ferent odors  ;  the  blood  of  animals  also  differed  in  this  respect  very  per- 
C"ptib!y  from  that  of  man. 


THEIR  MODE  OF  ACTION.  381 

All  these  conditions  for  contagion  must  be  considered  as  acci- 
dental. Their  formation  and  accumulation  in  the  body  may  be 
prevented,  and  they  may  even  be  removed  from  it  without  dis- 
turbing its  most  important  functions  or  health.  Their  presence 
is  not  necessary  to  life. 

The  action,  as  well  as  the  generation  of  the  matter  of  conta- 
gion is,  according  to  this  view,  a  chemical  process  participated 
in  by  all  substances  in  the  living  body,  and  by  all  the  constitu- 
ents  of  those  organs  in  which  the  vital  principle  does  not  over- 
come the  chemical  action.  The  contagion,  accordingly,  either 
spreads  itself  over  every  part  of  the  body,  or  is  confined  particu- 
larly to  certain  organs,  that  is,  the  disease  attacks  all  the  organs, 
or  only  a  few  of  them,  according  to  the  feebleness  or  intensity 
of  their  resistance. 

In  the  abstract  chemical  sense,  reproduction  of  a  contagion 
depends  upon  the  presence  of  two  substances,  one  of  which 
becomes  completely  decomposed,  but  communicates  its  own 
state  of  transformation  to  the  second.  The  second  substance 
thus  thrown  into  a  state  of  decomposition  is  the  newly-formed 
contagion. 

The  second  substance  must  have  been  originally  a  con- 
stituent of  the  blood :  the  first  may  be  a  body  accidentally 
present :  but  it  may  also  be  a  matter  necessary  to  life.  If  both 
be  constituents  indispensable  for  the  support  of  the  vital  func- 
tions of  certain  principal  organs,  death  is  the  consequence  of 
their  transformation.  But  if  the  absence  of  the  one  substance 
which  was  a  constituent  of  the  blood  do  not  cause  an  immediate 
cessation  of  the  functions  of  the  most  important  organs,  if  they 
continue  in  their  action,  although  in  an  abnormal  condition, 
convalescence  ensues.  In  this  case  the  products  of  the  trans- 
formations still  existing  in  the  blood  are  used  for  assimila- 
tion, and  at  this  period  secretions  of  a  peculiar  nature  are 
produced. 

When  the  constituent  removed  from  the  blood  is  a  product  of 
an  unnatural  manner  of  living,  or  when  its  formation  takes  place 
only  at  a  certain  age,  the  susceptibility  of  contagion  ceases  upon 
its  disappearance. 

The  effects  of  vaccine  matter  indicate  that  an  accidental  con. 


POISONS,  CONTAGIONS,  MIASMS. 


stituent  of  the  blood  is  destroyed  by  a  peculiar  process  of  decom- 
position, which  does  not  affect  the  other  constituents  of  the  circu- 
lating fluid. 

If  the  manner  in  which  the  precipitated  yeast  of  Bavarian  beer 
acts  be  called  to  mind,  the  modus  operandi  of  vaccine  lymph  can 
scarcely  be  matter  of  doubt. 

Both  the  kind  of  yeast  here  referred  to  and  the  ordinary 
ferment  are  formed  from  gluten,  just  as  the  vaccine  virus  and 
the  matter  of  small-pox  are  produced  from  the  blood.  Ordinary 
yeast  and  the  virus  of  human  small-pox,  however,  effect  a 
violent  tumultuous  transformation,  the  former  in  vegetable 
juices,  the  latter  in  blood,  in  both  of  which  fluids  respectively 
their  constituents  are  contained,  and  they  are  reproduced  from 
these  fluids  with  all  their  characteristic  properties.  The  preci- 
pitated yeast  of  Bavarian  beer,  on  the  other  hand,  acts  entirely 
upon  the  sugar  of  the  fermenting  liquid,  and  occasions  a  very 
protracted  decomposition  of  it,  in  which  the  gluten  which  is 
also  present  takes  no  part.  But  the  air  exercises  an  influence 
upon  the  latter  substance,  and  causes  it  to  assume  a  new  form 
and  nature,  in  consequence  of  which  this  kind  of  yeast  also  is 
reproduced. 

The  action  of  the  virus  of  cow-pox  is  analogous  to  that  of  the 
low  yeast ;  it  communicates  its  own  state  of  decomposition  to  a 
matter  in  the  blood,  and  from  a  second  matter  is  itself  regene- 
rated, but  by  a  totally  different  mode  of  decomposition  ;  the  pro- 
duct posse&ses  the  mild  form,  and  all  the  properties  of  the  lymph 
of  cow-pox. 

The  susceptibility  of  infection  by  the  virus  of  human  small- 
pox must  cease  after  vaccination,  for  the  substance  to  the  pre- 
sence of  which  this  susceptibility  is  owing  has  been  removed 
from  the  body  by  a  peculiar  process  of  decomposition  artificially 
excited.  But  this  substance  may  be  again  generated  in  the  same 
individual,  so  that  he  may  again  become  liable  to  contagion ;  and 
a  second  or  third  vaccination  will  again  remove  the  peculiar  sub- 
stance from  the  system. 

Chemical  actions  are  propagated  in  no  organs  so  easily  as  in 
the  lungs  ;  and  it  is  well  known  that  diseases  of  the  lungs  are, 
above  all  others,  frequent  and  dangerous. 


THEIR  MODE  OF  ACTION.  393 

If  it  is  assumed  that  chemical  action  and  the  vital  principle 
mutually  balance  each  other  in  the  blood,  it  must  further  be  sup- 
posed that  the  chemical  powers  will  have  a  certain  degree 
of  preponderance  in  the  lungs,  where  the  air  and  blood  are  in 
immediate  contact ;  for  these  organs  are  fitted  by  nature  to  favor 
chemical  action  ;  they  do  not  offer  resistance  to  the  changes 
experienced  by  the  venous  blood. 

The  contact  of  air  with  venous  blood  is  limited  to  a  very  short 
period  of  time  by  the  motion  of  the  heart,  and  any  change  beyond 
a  determinate  point  is,  in  a  certain  degree,  prevented  by  the 
rapid  removal  of  the  blood  which  has  become  arterialized.  Any 
disturbance  in  the  functions  of  the  heart,  and  any  chemical 
action  from  without,  even  though  weak,  occasions  a  change  in 
the  process  of  respiration.  Solid  substances,  also,  such  as  dust 
from  vegetable,  animal,  or  inorganic  bodies,  act  in  the  same  way 
as  they  do  in  a  saturated  solution  of  a  salt  in  the  act  of  crystal- 
lization, that  is,  they  occasion  a  deposition  of  solid  matters  from 
the  blood,  by  which  the  action  of  the  air  upon  the  latter  is  altered 
or  prevented. 

When  gaseous  and  decomposing  substances,  or  those  which 
exercise  a  chemical  action,  such  as  sulphuretted  hydrogen  and 
carbonic  acid,  obtain  access  to  the  lungs,  they  meet  with  less 
resistance  in  this  organ  than  in  any  other.  The  chemical  pro- 
cess of  slow  combustion  in  the  lungs  is  accelerated  by  all  sub- 
stances in  a  state  of  decay  or  putrefaction,  by  ammonia  and  alka- 
lies ;  but  is  retarded  by  empyreumatic  substances,  volatile  oils, 
and  acids.  Sulphuretted  hydrogen  produces  immediate  decom- 
position of  the  blood,  and  sulphurous  acid  combines  with  the 
substance  of  the  tissues,  the  cells,  and  membranes. 

When  the  process  of  respiration  is  modified  by  contact  with  a 
matter  in  the  progress  of  decay,  when  this  matter  communicates 
the  state  of  decomposition,  of  which  it  is  the  subject,  to  the  blood, 
disease  is  produced. 

If  the  matter  undergoing  decomposition  is  the  product  of  a  dis- 
ease, it  is  called  contagion ;  but  if  it  is  the  product  of  the  decay 
or  putrefaction  of  animal  and  vegetable  substances,  or  if  it  acts 
by  its  chemical  properties  (not  by  the  state  in  which  it  is),  and 


3S4  POISONS,  CONTAGIONS,  MIASMS. 

iherefore  enters  into  combination  with  parts  of  the  body,  or  causes 
their  decomposition,  it  is  termed'MiASM. 

Gaseous  contagious  matter  is  a  miasm  emitted  from  blood,  and 
capable  of  generating  itself  again  in  living  blood. 

But  miasm,  properly  so  called,  causes  disease  without  being 
itself  reproduced. 

All  the  observations  hitherto  made  upon  gaseous  contagious 
matters  prove,  that  they  also  are  substances  in  a  state  of  decom- 
position. When  vessels  filled  with  ice  are  placed  m  air  impreg- 
nated with  gaseous  contagious  matter,  their  outer  surfaces 
become  covered  with  water  containing  a  certain  quantity  of  this 
matter  in  solution.  This  water  soon  becomes  turbid,  and,  in 
common  language,  putrefies,  or,  to  describe  the  change  more 
correctly,  the  process  of  decomposition  of  the  dissolved  contagious 
matter  is  completed  in  the  water. 

All  gases  emitted  from  putrefying  animal  and  vegetable  sub- 
stances in  processes  of  disease,  generally  possess  a  peculiar 
nauseous  offensive  smell,  a  circumstance  which,  in  most  cases, 
proves  the  presence  of  a  body  in  a  state  of  decomposition,  that  is, 
of  chemical  action.  Smell  itself  may,  in  many  cases,  be  con- 
sidered as  a  reaction  of  the  nerves  of  smell,  or  as  a  resistance 
offered  by  the  vital  powers  to  chemical  action. 

Many  metals  emit  a  peculiar  odor  when  rubbed,  but  this  is  the 
case  with  none  of  the  noble  metals,' — those  which  suffer  no 
change  when  exposed  to  air  and  moisture.  Arsenic,  phos- 
phorus, musk,  the  oil  of  linseed,  lemons,  turpentine,  rue,  and 
peppermint,  possess  an  odor  only  when  they  are  in  the  act 
of  eremacausis  (oxidation  at  common  temperatures). 

The  odor  of  gaseous  contagious  matters  is  owing  to  the  same 
cause ;  but  it  is  also  generally  accompanied  by  ammonia,  which 
may  be  considered,  in  many  cases,  as  the  means  through  which 
the  contagious  matter  receives  a  gaseous  form,  just  as  it  is  the 
means  of  causing  the  smell  of  innumerable  substances  of  little 
volatility,  and  of  many  which  have  no  odor.     (Robiquet.)* 

Ammonia  is  very  generally  produced  in  cases  of  disease ;  it  is 
always  emitted  in  those  in  which  contagion  is  generated,  and  is 

,        *  Ann.  de  Chim.  et  de  Phys.,  XV.,  27. 


THEIR  MODE  OF  ACTION.  385 

ail  invariable  product  of  the  decomposition  of  animal  matter. 
The  presence  of  amnionia  in  the  air  of  chambers  in  which  dis- 
eased patients  iie,  j)articularly  of  those  afflicted  with  a  contagious 
disease,  may  be  readily  detected  ;  for  the  moisture  condensed  by 
ice  in  the  manner  just  described,  produces  a  white  precipitate  in 
a  solution  of  corrosive  sublimate,  just  as  a  solution  of  ammonia 
does.  The  ammoniacal  salts,  also,  obtained  by  the  evaporation 
of  rain-water  after  an  acid  has  been  added,  when  treated  with 
Inne  so  as  to  set  free  their  ammonia,  emit  an  odor  most  closely 
resembling  that  of  corpses,  or  the  peculiar  smell  of  dunghills. 

By  evaporating  acids  in  air  containing  gaseous  contagions,  the 
ammonia  is  neutralized,  and  we  thus  prevent  further  decomposi- 
tion, and  destroy  the  power  of  the  contagion,  that  is,  its  state  of 
chemical  change.  Muriatic  and  acetic  acids,  and,  in  several 
cases,  nitric  acid,  are  to  be  preferred  for  this  purpose  before  all 
others.  Chlorine,  also,  is  a  substance  which  destroys  ammonia 
and  organic  bodies  with  much  facility  ;  but  it  exerts  such  an 
injurious  influence  upon  the  lungs,  that  it  may  be  classed 
amongst  the  most  puisunous  bodies  known,  and  should  never  be 
employed  in  places  in  which  men  breathe. 

Carbonic  acid  and  sulphuretted  hydrogen,  which  are  fre- 
quently evolved  from  the  earth  in  cellars,  mines,  wells,  sewers, 
and  other  places,  are  amongst  the  most  pernicious  miasms.  The 
former  may  be  removed  from  the  air  by  alkalies  ;  the  latter,  by 
burning  sulphur  (sulphurous  acid),  or  by  the  evaporation  of  nitric 
acid. 

The  characters  of  many  organic  compounds  are  well  worthy 
of  the  attention  and  study  both  of  physiologists  and  pathologists, 
more  especially  in  relation  to  the  mode  of  action  of  medicines 
and  poisons. 

Several  of  such  compounds  are  known,  which  to  all  appear- 
ance are  quite  indifferent  substances,  and  yet  cannot  be  brought 
into  contact  with  one  another  in  water  without  suffering  a  com- 
plete transformation.  All  substances  which  thus  suffer  a  mutual 
decomposition,  possess  complex  atoms  ;  they  belong  to  the  highest 
order  of  chemical  compounds.  For  example,  amygdalin,  a  con- 
stituent of  bitter  almonds,  is  a  perfectly  neutral  body,  of  a  slightly 
bitter  taste,  and  very  easily  soluble  in  water.  But  when  it  is 
18 


386  POISONS,  CONTAGIONS,  MIASMS. 


introduced  into  a  watery  solution  of  synaptas  (a  constituent  of 
sweet  almonds),  it  disappears  completely  without  the  disengage, 
ment  of  any  gas,  and  the  water  is  found  to  contain  free  hydro- 
cyanic acid,  hydruret  of  benzule  (oil  of  bitter  almonds),  a  pecu- 
liar acid  and  sugar,  all  substances  of  which  merely  the  elements 
existed  in  the  amygdalin.  The  same  decomposition  is  effected 
when  bitter  almonds,  which  contain  the  same  white  matter  as  the 
sweet,  are  rubbed  into  a  powder  and  moistened  with  water. 
Hence  it  happens  that  bitter  almonds,  pounded  and  digested  in 
alcohol,  do  not  yield  oil  of  bitter  almonds  containing  hydrocyanic 
acid,  by  distillation  with  water ;  for  the  substance  which  occa- 
sions the  formation  of  those  volatile  substances,  is  dissolved  by 
alcohol  without  change,  and  is  therefore  extracted  from  the 
pounded  almonds.  Pounded  bitter  almonds  do  not  contain 
amygdalin,  after  having  been  moistened  with  water,  for  that  sub. 
stance  is  completely  decomposed  when  they  are  thus  treated. 

Volatile  compounds  cannot  be  detected  by  their  smell  in  the 
seeds  of  the  Sinapis  alba  and  «S.  nigra.  A  fixed  oil  of  a  mild 
taste  is  obtained  from  them  by  pressure,  but  no  trace  of  a  volatile 
substance.  If,  however,  the  seeds  are  rubbed  to  a  fine  powder, 
and  subjected  to  distillation  with  water,  a  volatile  oil  of  a  very 
pungent  taste  and  smell  passes  ovei  along  with  tJie  steam.  But 
if,  on  the  contrary,  the  seeds  are  trej^ted  with  alcohol  previously 
to  their  distillation  with  water,  the  residue  does  not  yield  a  vola- 
tile  oil.  The  alcohol  contains  a  crys-aiiinf  body  called  sinapin, 
and  several  other  bodies.  These  do  not  possess  the  characteristic 
pungency  of  the  oil,  but  it  is  by  the  contact  of  them  with  water, 
and  with  the  albuminous  constituents  of  the  seeds,  that  the  vola- 
tile oil  is  formed. 

Thus  bodies  which  would  be  regarded  as  absolutely  indifferent 
in  inorganic  chemistry,  on  account  of  their  possessing  no  promi- 
nent chemical  characters,  when  placed  in  contact  with  one 
another,  are  mutually  decomposed.  Their  constituents  arrange 
themselves  in  a  peculiar  manner,  so  as  to  form  new  combina- 
tions ;  a  complex  atom  dividing  into  two  or  more  atoms  of  less 
complex  constitution,  in  consequence  of  a  mere  disturbance  in 
the  attraction  of  their  elements. 

The  white  constituents  of  the  almonds  and  mustard,  which 


THEIR  MODE  OF  ACTION.  3&7 


resemble  coagulated  albumen,  must  be  in  a  peculiar  state,  ia 
order  to  exert  their  action  upon  amygdalin,  and  upon  those  con. 
stituents  of  mustard  from  which  the  volatile  pungen?  jil  is 
produced.  If  almonds,  after  being  blanched  and  pounded,  are 
thrown  into  bailini>  water,  or  treated  with  hot  alcohol,  with 
mineral  acids,  or  '.vjth  salts  of  mercury,  their  power  to  effect  a 
decomposition  in  amygdalin  is  completely  destroyed.  Synaptas 
is  an  azolized  body  which  cannot  be  preserved  when  dissolved  in 
water.  Its  solution  becomes  rapidly  turbid,  deposits  a  white  pre- 
cipitate, and  acquires  the  offensive  smell  of  putrefying  bodies. 

It  is  exceedingly  probable  that  the  peculiar  state  of  transposi- 
tion into  which  the  elements  of  synaptas  are  thrown  when  dis- 
solved in  water,  may  be  the  cause  of  the  decomposition  of  amyg- 
dalin, and  formation  of  the  new  products  arising  from  it.  The 
action  of  synaptas,  in  this  respect,  is  very  similar  to  that  of  rennet 
upon  sugar. 

Malt,  and  the  germinating  seeds  of  com  in  general,  contain  a 
substance  called  diastase,  which  is  formed  from  the  gluten  con- 
tained, in  them,  and  cannot  be  brought  in  contact  with  starch  and 
water  without  effecting  a  change  in  the  starch. 

When  bruised  malt  is  strewed  upon  warm  paste  of  starch,  the 
paste,  after  a  few  minutes,  becomes  quite  liquid,  and  the  water 
is  found  to  contain,  in  place  of  starch,  a  substance  in  many 
respects  similar  to  gum.  But  when  more  malt  is  added,  and  the 
heat  longer  continued,  the  liquid  acquires  a  sweet  taste,  and  all 
the  starch  is  found  to  be  converted  into  sugar  of  grapes. 

The  elements  of  diastase  have  at  the  same  time  arranged 
themselves  into  new  combinations. 

The  conversion  of  the  starch  contained  in  food  into  sugar  of 
grapes,  in  diabetes  mellitus,  indicates  that  anion n^st  the  convStitu- 
ents  of  some  one  organ  of  the  body  a  substance  or  substances 
exist  in  a  state  of  chemical  action,  to  which  the  vital  principle  of 
the  diseased  organ  does  not  oppose  lesistance.  The  component 
parts  of  the  organ  must  suffer  changes  simultaneously  with  the 
starcli,  so  that  the  more  starch  is  furnished  to  it,  the  more  ener- 
getic and  intense  the  disease  must  become  ;  while  if  only  food 
incapable  of  suffering  such  transformation  from  the  same  cause 
.8  supplied,  and  the  vital  energy  is  strengthened  by  stimulant 


388  POISONS,  CONTAGIONS,  MIASMS. 

remedies  and  strong  nourishment,  the  chemical  action  may  finally 
be  subdued,  or,  in  other  words,  the  disease  cured. 

The  conversion  of  starch  into  sugar  may  also  be  effected  by 
pure  gluten,  and  by  dilute  mineral  acids. 

From  all  the  preceding  facts,  we  see  that  very  various  trans- 
positions, and  changes  of  composition  and  properties,  may  be 
produced  in  complex  organic  molecules,  by  every  cause  which 
occasions  a  disturbance  in  the  attraction  of  their  elements. 

When  moist  copper  is  exposed  to  air  containing  carbonic  acid, 
the  contact  of  this  acid  increases  the  affinity  of  the  metal  for  the 
oxygen  of  the  air  in  so  great  a  degree  that  they  combine,  and 
the  surface  of  the  copper  becomes  covered  with  green  carbonate 
of  copper.  Two  bodies  which  possess  the  power  of  combining 
together,  assume,  however,  opposite  electric  conditions  at  the 
moment  in  which  they  come  in  contact. 

When  copper  is  placed  in  contact  with  iron,  a  peculiar  electric 
condition  is  excited,  in  consequence  of  which  the  property  of  the 
copper  to  unite  with  oxygen  is  destroyed,  and  the  metal  remains 
quite  bright. 

When  formate  of  ammonia  is  exposed  to  a  temperature  of 
388°  F.  (IBQo  C),  the  intensity  and  direction  of  the  chemical 
force  undergo  a  change,  and  the  conditions  under  which  the  ele- 
ments of  this  compound  are  enabled  to  remain  in  the  same  form 
cease  to  be  present.  The  elements,  therefore,  arrange  them- 
selves in  a  new  form ;  hydrocyanic  acid  and  water  being  the 
results  of  the  change. 

Mechanical  motion,  friction,  or  agitation,  is  sufficient  to  cause 
a  new  disposition  of  the  constituents  of  fulminating  silver  and 
mercury,  that  is,  to  effect  another  arrangement  of  their  element?, 
or  to  cause  the  production  of  new  compounds  in  a  liquid. 

We  know  that  electricity  and  heat  possess  a  decided  influence 
upon  the  exercise  of  chemical  affinity  ;  and  that  the  attractions 
of  substances  for  one  another  are  subordinate  to  numerous  causes 
which  change  the  condition  of  these  substances  by  altering  the 
direction  of  their  attractions.  In  the  same  manner,  therefore,  the 
exercise  of  chemical  powers  in  the  living  oi^anism  is  dependent 
upon  the  vital  principle. 

The  power  of  elements  to  unite  together,  and  to   form  the 


THI^IR  MODE  OF  ACTION. 


peculiar  compounds,  which  are  generated  in  animals  and  vegeta- 
bles, is  chemical  affinity  ;  but  the  cause  by  which  they  are  pre  - 
vented  from  arranging  themselves  according  to  the  degrees  of 
their  natural  attractions — the  cause,  therefore,  by  which  they  are 
made  to  assume  their  peculiar  order  and  form  in  the  body,  is  the 
vital  principle. 

After  the  removal  of  the  cause  which  produced  their  union — 
that  is,  after  the  extinction  of  life — most  organic  atoms  retain 
their  condition,  form,  and  nature,  only  by  a  vis  inertice ;  for  a 
great  law  of  nature  proves  that  matter  does  not  possess  the  power 
of  spontaneous  action.  A  body  in  motion  loses  its  motion  only 
when  a  resistance  is  opposed  to  it :  and  a  body  at  rest  cannot  be 
put  in  motion,  or  into  any  action  whatever,  without  the  operation 
of  some  exterior  cause. 

Tlie  same  numerous  causes  which  are  opposed  to  the  forma- 
tion of  complex  organic  molecules,  under  ordinary  circumstances, 
occasion  their  decomposition  and  transformations  when  the  only 
antagonist  power,  the  vital  principle,  no  longer  counteracts  the 
influence  of  those  causes.  Contact  with  air  and  the  most  feeble 
chemical  action  now  effect  changes  in  the  complex  molecules ; 
even  contact  with  any  body,  the  particles  of  which  are  under- 
going motion  or  transposition,  is  often  sufficient  to  destroy  their 
state  of  rest,  and  to  disturb  their  statical  equilibrium  in  the 
attractions  of  their  constituent  elements.  An  immediate  con- 
sequence of  this  is,  that  they  arrange  themselves  according  to  the 
different  degrees  of  their  mutual  attractions,  and  that  new  com- 
jjounds  are  formed,  m  which  chemical  affinity  has  the  ascendency^ 
and  opposes  any  further  change,  as  long  as  the  conditions  undof 
which  these  compoun<ls  w^ere  formed  remain  unaltered. 


APPENDIX  TO  PART  II 


Some  potatoes,  which  had  been  wrapped  in  several  folds  of  paper, 
placed  in  a  box,  and  kept  in  a  dark  but  moderately  warm  place 
in  the  laboratory,  were  found  in  March  to  be  enveloped  in  a  kind 
of  net,  formed  of  sprouts  of  two  lines  in  thickness,  and  10  to  15 
inches  in  length.  On  these  sprouts  there  were  several  hundred 
small  tubers,  of -f-  to  ^  of  an  inch  in  thickness.  The  sprouts  and 
the  tubers  possessed  a  white  color,  and  did  not  exhibit  any  signs  of 
leaves.  On  examining  the  parent  potatoe  with  a  microscope,  it 
was  found  that  its  exterior  cells  were  still  partly  filled  with 
granules  of  starch  ;  but  the  interior  was  quite  empty,  and  its 
substance  soft  and  elastic.  The  sprouts  and  the  cells  of  the 
young  potatoes  abounded  in  starch. 

The  growth  of  these  sprouts,  and  the  formation  of  the  tubers 
at  the  expense  of  the  constituents  of  the  potatoes,  give  a  good 
illustration  of  the  formation  and  nutrition  of  fungi.  The  organic 
substance  present  in  the  potatoe  obtains  a  new  form  by  means  of 
the  active  power  resident  in  the  germ  ;  for,  in  this  case,  it  cannot 
be  supposed  that  the  food  was  extracted  from  the  air.  Now,  just 
as  the  constituents  of  the  old  potatoe  entered  into,  and  were  again 
found  unchanged  in  the  sprouts  of  the  young  ones,  in  like  man- 
ner animal  and  vegetable  substances  in  a  state  of  decay  enter 
into  the  fungi  arising  from  them.  Thus  the  ingredients  of  these 
bodies,  as  the  products  of  iheir  putrefaction,  pass  over  into  the 
fungi,  exactly  as  the  interior  substance  of  the  parent  potatoe  enters 
into  the  sprouts  and  young  tubers.     For  this  conversion  organic 


392  APPENDIX. 


power  alone  is  sufficient,  and  light  and  other  conditions  of  vegc 
table  life  may  be  entirely  excluded. 


TABLE 

SHOWING   THE   PROPORTION   BETWEEN  THE   ENGLISH   AND   HESSIAH 
STANDARD   OF   WEIGHTS    AND     MEASURES. 

1  lb.  English  is  equal  to  0*90719  lbs.  Hessian. 

1  Hessian  acre  is  equal  to  26,910  English  square  feet. 

1  En^clish  square  foot  is  equal  to  1  •4S64  Hessian  square  feet. 

1  English  cubic  foot  contains  r81218  of  a  Hessian  cubic  foot 


INDEX 


Absorption,  by  roots,  64 

Of  salts,  72 
Acid,  acetic,  transformation  of,  280 

Formation  of,  302-310 

Boracic,  77 

Carbonic,  3 

contained    in    the    atmo- 
sphere, 14 

decomposed  by  plants,  1 5 

disintegrates  rocks,  113  • 

is  furnished  by  humus,  29 

is  expired  by  animals,  16 

-: is  a  product  of  decay,  299 

why  necessary  to  plants,  64 

Cyanic,  84 

Formic,  41 
Hippuric,  49 
Humic,  5 

properties  of,  5 

contains  ammonia,  6 

Hydrocyanic,  266 

Kinic,  71 

Meconic,  71 

Melanlc,  29S 

Nitric,  214,  306 

Phosphoric,  in  ashes  of  plants, 

116 
Rocellic,  in  plants,  65 
Succinic,  343 
Sulphuric,  a  source  of  sulphur, 

60 

retains  ammonia,  181 

action  on  soils,  185 

Acids,  action  of,  upon  sugar,  278 
Arrest  decay,  296 
Capacity  of  saturation,  6b 
Organic,  in  plants,  3,  65 

how  formed,  l38 

— —  essential  to  formation  of 

sugar,  137 


Agave  americaxa,  absorbs   oxy 

gen,  22 
Agriculture,  object  of,  lOS 

How  attained,  lOS 

Its  importance,  107 

A  principle  in,  179 

Science  necessary  to,  124 
Air,  access  of,  favored,  29 

Ammonia  in,  43 

Carbonic  acid  in,  14 

Effect  of  upon  juices,  302 

— »—  on  soils,  82 

Improved  by  plants,  16 

Necessary  to  respiration,  167 

to  plants,  96 

Nitric  acid  contained  in,  218 
Albumen,  5S,  134 
Alcohol,  effect  of  heat  on,  281 

Products  of  its  oxidation,  299 

From  sugar,  287 
Alkalies,  contained  in  soils,  S3,  92, 
111 

Essential   to   the   formation  of 
sugar,  starch,  and  gum,  187 

Necessity  for  restoring  to  soils, 
113 

Promotes  decay  of  wood,  341 

Quantity  of  in  aluminous  mine- 
rals, 111 

Use  of  ir.  pk.nts,  121 
Alkalins  Bases,  in  plants,  on  what 
their  existence  depends,  70 

Salts  in  plants,  sourcej*  of,  114 

— —  contained  in  fertile  soils, 
114 

•  —  liberaUjd  from  soils,  by  th« 
action  of  air  and  of  lime,  128 
Alloxan,  3?4 
Alloxantin,  307 
Alumina,  in  fertile  soils,  110 

its  influence  on  vegetation,  llJ 


394 


INDEX. 


Ammonia,  carbonate  of,  in  air,  43 

How  fixed,  181 

Cause  of  nitrification,  309 

Changes  colors,  41 

Condensed  by  charcoal,  50 

Conversion  of,  into  nitric  acid, 
309 

Early  existence  of,  206 

Evolved  from  n\anure,  51 

Fixed  by  gypsum,  182 

Contained  in  beet-root,  46 

maple  juice,  46 

privies,  182 

stables,  182 

Furnishes  nitrogen,  57 

Deductions  of  Boussingault  con- 
cerning, 199 

Boussingault's    deductions     are 
erroneous,  200 

Is  not  an  essential  constituent 
of  manure,  202 

Is  always  of  use  in  manure,  203 

Loss  from  evaporation,  182 

Inorganic  origin  of,  78 

Product  of  decay,  42 

Properties  of,  41 

Quantity  absorbed  by  charcoal, 
56 

by  decayed  wood,  56 

In  rain-water,  44 

In  humus,  6 

In  snow-water,  44 

Separated  from  soils  by  rain,  56 

Solubility  of,  43 

Transformations  of,  41 

Product  of  disease,  384 
Analysis  of  ashes  of  great  import- 
ance, 203 
Animal,  food,  preservation  of,  304 

Life,  dependent  on  plants,  57 

processes  of,  167 

Matter,  products  of  decay  of,  57 

essential   to   nitrification, 

214 
Animals,  excrements  of,  how  form- 
ed, 50,  51 

Faeces  of,  contain  little  nitrogen, 
50 

Liquid  excrements  of,  rich  in 
nitrogen,  48 

Obtain  their  fundamental  sub- 
stances from  plants,  60 
Annual  plants,  how  nourished,  99 

AWTHOXANTHUM    ODORATVM,    acid 

«»,40 


Anthracite,  353 
Antidotes  to  poisons,  362 
Apatite,  117,  118 
Arable  land,  formation  of,  82 
Argillaceous  earth.  111 
Aromatics,  their  influence  on  fer- 
mentation, 315 
Arsenious  acid,  action  of,  361 
Ashes,   analysis  of  various   plants. 
See  pages  68,  143,  1.50,  203, 
and  Appendix  to  Part  I.,  230- 
254 

As  a  manure,  175 

Of  bones,  185 

Of  peat,  186 

Of  coals,  178 

Of  wood,  176 
Assimilation  of  carbon,  3-27 

Of  carbonic  acid  and  ammonia' 
98 

Of  hydrogen,  35-39 

Of  nitrogen,  40-58 
Atmosphere,  ammonia  in,  43 

Carbonic  acid  in,  15 

Composition  is  invariable,  13 

Motion  of,  19 
Atoms,  motions  of,  271 

Permanence  in  position  of,  271 
Azotized  matter  in  juices  of  plants 
102 

Substances,  combustion  of,  307 

B. 
Bark  of  trees  viewed  as  exeremen- 
titious,  164 

Of  fir,  analysis  of  its  ashes,  164 
Barley,  analysis  of  its  ashes,  150 

Experiment  oa,  22S 
Basalt,  analysis  of,  88 
Bases,  alkaline  in  plants,  on  what 
their  existence  depends,  70 

Organic,  4,  71 

Oxygen  contaiae.I  ;ii,  67 

In  plants,  65-81 

Substitution  of,  68,  70 
Beans,  analysis  of  ashes  of,  143 

Contain  casein,  135 

Nutritive  power  of,  134 
Beech,  analysis  of  its  ashes,  248 
Beer,  319 

Bavarian,  319 
Beet,  analysis  of,  12 

Ammonia  contained  in,  46 

From  sandy  soils,  104 
BxTNiONANT  diseoM,  380 


INDEX. 


305 


Benzoic  acid,  formed,  48 
Birch  tree,  ammonia  in,  46 
Bix>oi),  analysis  of  its  ashes,  142 

Action  of  chemical  agents  upon, 
374 

Its  feeble  resistance  to  exterior 
influences,  374 

Organic  salts  in,  357 

Its  character,  367 
Blossoms,  when  produced,  32 

Increased,  98 
Bones,  dust  of,  178,  185 

Durability  of,  185 

Gelatine  in,  186 
BoRACic  acid,  78 
Bouquet  of  wines,  316 
Brandy  from  corn,  315 

Oil  of,  316 
Brazil,  wheat  in,  114 
Brown  Coal,  348 
Buckwheat,  223 


Cactus,  34 

Calcium,  fluoride  of,  119 

Chloride  of,  181 
Caoutchouc,  in  plants,  34 
Carbon,  assimilation  of,  3,  28 

Of  decaying  substances,  seldom 
affected  by  oxygen,  299 

Derived  from  air,  15 

In  sea-water,  80 

Produce  of,  in  land,  12 

in  beet,  12 

in  straw,  12 

Restored  to  so4,  32 

Received  by  It^^es,  16 
Carbonate  of  ammonia,  contained 
in  rain-water,  44 

Decomposed  by  gypsum,  180 

Of  lime  in  caverns  and  vaults, 
94 
Carbonic  j^cid  in  the  atmosphere, 
13 

Changes  in  the  leaves,  106 

Decomposed  by  plants,  19 

Decomposes  soils,  83 

Emission  of,  at  night,  26 

Evaporation  of,  27 

Evolution  from  decaying  b<  dies, 
299-302 

From  humus,  29 

respiration,  167 

woody  fibre,  338 

tnorease  of,  prevented,  16 


Carbonic  acid — continued. 

Influerxe  of  light  on  its  decom- 
position, 106 
Carburetted     hydrogen,     with 

coal,  368 
Caverns,  stalactites  in,  94 
Charcoal,  condenses  ammonia,  56 

Promotes  growth  of  plants,  185 
Chemical  effects  of  light,  106 

Processes  in  the   nutrition    of 
vegetables,  2 

Transformations,  265,  275 
Chemistry,  organic,  what  it  is,  1 
Chloride  of  calcium,  181 

Of  potassium,  72 

Of  sodium,  its  volatility,  79 
Clay  slate,  88,  89,  118 
Clays,  formation  of,  90 

From  porphyry,  90 

From  felspar,  91 

Potash  in,  111 
Clay,  burned,  how  it  acts  as  ma- 
nure, 55, 130 
Coal,  formation  of,  346-354 

Inflammable  gases  from,  353 

Of  humus,  5 

Wood  or  brown,  348-352 
Colors  of  flowers,  41 
Combustion  at  low  temperatures, 
300 

Of  decayed  wood,  342 

Induction  of,  270,  306 

Respiration,  viewed  as,  169 

Spontaneous,  297 
Concretions  from  horses,  118 
Constituents  of  the  blood  exist  in 
plants,  60 

The  formation  of,  the  main  ob- 
ject of  agriculture,  53 
Contagion,    reproduction    of,     on 
what  dependent,  377,  378 

Susceptibility  to,  how  occasion- 
ed, 373 
Contagions,  how  produced,  376-378 

Propagation  of,  377-384 
Contagious  matters,  action  of,  376, 
379,  383 

Their  effects  explained,  353, 377 

Life  in,  disproved,  353,  377 

Reproduction  of  353,  377-378 
Copper,  oxide  of,  in  clay  slate,  118 
Corn,  how  cultivated  in  Italy,  114 
Corn  brandy,  314 
Corrosive   subumatk,  acticsn   of 
361 


SS6 


in:)ex. 


Cow-pox,  action  of  virus  of,  3S2 
Cow,  urine  of,  analysis,  169,  256, 257 
Crops,  rotation  of,  136,  165 
Cultivation,  its  benefits,  19 

Different  methods  of,  lOS 

Object  of,  109 
Culture,  art  of,  93-122 
Cyanic  acid,  transformation  of,2S5 
Cyanogen,  combustion  of,  310 

Transformation  of,  2S6 

D. 
Darwin  on  the  formation  of  soils,  83 

Descriptions  of  the  gold  ores  in 
Chili,  126 
Death,  the  source  of  life,  58 
Decay,  295 

A  source  of  ammonia,  42 

Of  wood,  338 

And  putrefaction,  273 
Decomposition,  207 
Diamond,  its  origin,  343 
Diastase,  118 

Contains  nitrogen,  119 
Disease,  how  excited,  355-390 
Disintegration  of  rocks,  89 

Of  ores,  126 
Dung  of  the  nightingale,  262 

E. 
Ebony  wood,  oxygen  and  hydrogen 

in,  24 
Elements  of  plants,  3 
Eremacai/sis,  295-310 

Analogous'to  putrefaction,  301 

Arrested,  296 

Definition  of,  295 

Necessary  to  nitrification,  307 

Of  bodies  ccmUining  nitrogen, 

307 
Of  bodies  destitute  of  nitrogen, 
303 
Ether,  oenanthic,  316 
Excrementitious    matter,    pro- 
duction of,  illustrated,  168 
Excrement,  animal,  its  chemical 
nature,  169 
Of  the  cow,  horse,   &c.,  169, 
170,  255-266 
Excrements,  manure  in  which  they 
are  found,  169 
Of  animals,  contain  the   same 
amount  of  nitrogen,   as  that 
present  in  the  food,  169 


Excrements — continued. 

Of  plants,  32 

Conversion  of,  into  humus,  33 

Of  man,  amount  of,  172,  173 
Excretion,  organs  of,  167 

Of  plants,  theory  of,  32 

F. 
Fallow,  123-133 
Felspar,  decomposition  of,  90 
Analysis  of,  86 
Various  kinds  of,  86 
Decomposed  analysis  of,  90 
Ferment,  289 
Fermentation,  287,  311-337 

Ascribed  to  fungi,  and  infusoria, 

320-337 
Of  Bavarian  beer,  319,  325 
Of  beer,  311 
Gay-Lussac's    experiments    in, 

329 
Of  sugar,  287 
Of  vegetable  juices,  288 
Vinous,  311 
Of  wort,  312 
Fertility  of  fields,  how  preserved, 

174 
Fibrin,  58,  135 

Fires,  plants  on  localities  of,  116 
Fir  bark,  analysis  of  its  ashes,  104 

Wood,  analysis  of  its  ashes,  164 
Fishes  in  salt  pans,  77 
Flesh,  effect  of  salt  on,  358 

Preserved  under  certain  circum- 
stances, 330,  33 J 
Fluorine  in  ancient  bones,  120 
Food,  effect  on  products  of  plants, 
105 
Of  young  plants,  97 
Transformation  and  assimilation 

of,  32 
Knowledge  of  its   composition 

essential,  133 
Undergoes    combustion   in    the 
body,  168 
Formation  of  wood,  103 
Franconia,  caverns  in,  94 
Fruit,  increased,  98 
Ripening  of,  38 
,  changes  attending,  99 

FUCUS    GIGANTEUS,  226 

Fungi,  supposed  to  cause  fermente* 
tion,  326-337 


INDEX. 


397 


Gjlseotts  substances   in   the   lungs, 

effect  of,  384 
Gastebostetts  acdxeatus,  in  salt- 
pans, 77 
Gav-Lttssac,  his  experiments,  327 
Germination  of  potatoes,  99 

Of  grain,  102 
Glue,  manure  from,  179 
Glttten,  conversion  of,  into  yeast, 
322 

Decomposition  of,  294 

Gas  from,  311 
Graijv,  germination  of,  102 
Grapes,  fermentation  of,  311 

Juice  of,  differences  in,  118 

Potash  in,  70 
Grauwacke,  soil  from,  113 
Guano,  4S,  161,  174,  258-262 
Gypsum,  experiment  with,  53 

Decomposed    by    carbonate    of 
ammonia,  182 

Decomposed  by  salt,  63 

Its  influence,  53 

Use  of,  182 

H. 
Hanover  tobacco,  238 
Havannah  tobacco,  analysis  of  its 

ashes,  238 
Hay,  analysis  of  ashes,  150,  236 

Carbon  in,  11 
Hebsian   and  English  weights  and 

measures,  392 
Horse,  urine  of  the,  169,  257,  258 

Concretions  in  the,  119 
HoRSE-DUNG,  analysis  of,  169,  231, 

237 
Hum  ATE  of  lime,  quantity  received 
by  plants,  9 

HUMIC   ACID,   5 

Sometimes  contains  ammonia,,  6 
Action  of,  93 
Properties  of,  5 
Is  not  contained  in  soils,  7 
Quantity  received  by  plants,  9 
Insolubility  of,  93 
Humus,  5 

Action  of,  93 
Analysis  of,  6 
Erroneous  opinions  concerning, 

7 
Action  upon  oxygen,  92,  93 
Coal  of,  5 


Humus — continued. 

Conversion  of  woody  fibre  into, 
338 

How  produced,  5 

Its  insolubility,  93 

Properties  of,  5 

Sources  of  carbonic  acid,  93 

Theory  of  its  action,  93 
Hybernating  animals,  100 
Hydrogen,  assimilation  of,  35-39 

Excess   of  in  wood  accounted 
for,  36 

Of  decayed  wood,  340-342 

Of  plants,  source  of,  36 

Peroxide  of,  270 
Hyett,  Mr. ,  on  nitrate  of  soda,  223 


Ice,  bubbles  of  gas  in,  26 
lNGENHouss,,his  experiments,  21 
Ingredients   of  soil    removed  by 

crops,  148 
Inorganic  constituents   of  plants, 

64-81 

L. 
Lava,  soil  from,  110 
Lead,  salts  of,  compounds  with  or- 
ganic matter,  360 
Leaves,  absorb  carbonic  acid,  16 
Ashes  of,  contain  alkalies,  81 
Leaves  of  pine  and  fir — 

Cessation  of  their  functions,  32 
Change  color  from  absorption  of 

oxygen,  38 
Decompose  carbonic  acid,  16 
Their  office,  16 

Power  of  absorl)ing  nutriment, 
how  increased,  30 
Life,  notion,  of,  3f59 
Light,  absence  of>  its  effect,  22 
Chemical  effects  of,  105 
Influences  decomposition  of  car- 
bonic acid,  105 
Lime,  phosphate  of,  176-178 
Lime,  action  of,  128-131 
Lime-plants,  150 
Lime-tree  yields  su^ar,  103 
Limestones,  hydraulic,  91,  92,  130 


M. 
Magnesia,  phosphate  of,  in. 

64,  65 
Manure,  185-157 


sue 


INDEX. 


Manttre — continued. 

In  the  ashes  of  food  burned  in 

the  body,  148,  168 
Of  bones,  176,  185 
The  form  of,  important,  131 
Waste  of,  in  England,  159 
Animal,  yields  ammonia,  169 

Maple  juice,  ammonia  from,  46 
Trees,  sugar  of,  46 

Mesotype,  properties  of,  87 

Miasm,  defined,  384 

Morbid  poisons,  361-375 

Mosses  grow  luxuriantly  with  green 
light,  107 

Motion,  its  influence  on  chemical 
forces,  272 

MotTLD,  vegetable,  344 

Mouldering  of  bodies,  346 

N. 
Nitrate  of  soda  as  a  manure,  223 
Nitric  acid  from  ammonia,  218 

How  formed  215-217 
Nitrification,  307-310 
Nitrogen,  assimilation  of,  40-57 
In  excrements,  169 
In  plants,  4 

Production  of,  the  object  of  ag- 
riculture, 52 
Transformation  of  bodies  con- 
taining, 307 
Nutrition,  inorganic  substances  re- 
quisite in,  64 
Superfluous,  how  employed,  97 
Of  young  plants,  96 

0. 
Oaks,  ashes  of,  247 

Dwarf,  30 
Oak- WOOD,  composition  of,  247 
Odor  of  gaseous  contagious  matter, 

385 
CEnanthic  ether,  316 
Organic  acids,  1 40 

Decomposition  of,  140 

Chemistry,  1 
Oxygen,  absorption  of,  at  night,  21 

Absorption  of,  by  leaves,  38 

by  respiration,  167 

Absorption  of,  by  wood,  338-339 

Action  upon  woody  fibre,  ib. 

Emitted  by  leaves,  16 

In  air,  13 

Consumption  of,  14 

In  wuter.  36 


Oxygen — continued. 

Separated  during  the  formation 
of  acids,  140 

Is  furnished  by  the  decomposi- 
tion of  water,  36 

P. 
Peas  232 

Ashes  of,  143,  235,  250 
Ashes  of  straw,  238 
Peroxide  of  hydrogen,  270 
Phonolite,  analysis  of,  88 
Phosphates     are    constituents    of 

plants,  64,  67,  176,  178 
Phosphoric  acid  in  ashes  of  plants, 

64,  67,  176,  178 
Pine-tree  ashes,  68,  238,  240,  242, 

248,251,252 
Plants  absorb  oxygen,  21 

Analysis  of  ashes,  143,  235-254 
Characterized  by  their  principal 

mineral  ingredients,  149 
Decompose  carbonic  acid,  26,27 
Effect  of,  on  rocks,  89 
Elements  of,  4 
Exhalation     of    carbonic    acid 

from,  21 
Functions  of,  17 
Improve  the  air,  17 
Influence  of  gases  on,  22 
Mineral  ingredients  of,  64,  81 

149 
Life  of,  connected  with  that  of 

animals,  57 
Marine,  food  of,  157 
Milky-juiced,  in  barren  soils,  34 
Size  of,  proportioned  to  organs 

of  nourishment,  30 
Rotation  of,  its  advantage^  133 
Ploughing,  its  use,  128 
Poisoning,  superficial,  359 

By  sausages,  363 
Poisons,  generated  by  disease,  351 
seq. 
Inorganic,  356 
Peculiar  class  of,  361 
Rendered  inert  by  heat,  366 
Pompeii,  bones  from,  119 
Porphyry,  by  disintegrating,  fomui 

clay,  89 
Potash,  in  grapes,  70 
Plants,  150 
Replaced  by  soda,  70 
Quantity  in  soils*  111 


INDEX. 


999 


Potatoes,  germination  of,  Appen- 
dix to  Part  11,  391 
Purgative  effect  of  salts  explained, 

354 
Pus,  globules  in,  373 
Putrefaction,  25 

Communicated,  276,  363-378 
Source  of  ammonia,  57 

of  carbonic  acid,  57 

Putrefying  sausages,  death   from, 
364 
Their  mode  of  action,  365 
Substances,     their     effect    on 
wounds,  366 

alkaline,  375 

acid,  ib. 

R. 
Rain,  necessity  for,  to  furnish  alka- 
lies to  plants,  119 
Want  of,  or  excess  in,  producing 
diseases  in  plants,  120 
Rain-water,  contains  ammonia,  43 
Removal  of  branches,  effects  of,  97 
Rhododendron  ferrugineum,  97 
Ripening  of  fruit,  38 
Roots,  excrements  of,  73 
Rotation  of  crops,  133-165 
Rye,  143,  232,  233 

Ashes  of,  239,  249 

S. 
Saline  plants,  71 
Salt,  volatilization  of,  79 
Salts,  absorption  of,  73 

Effects  of,  on  the  organism,  352 

on  fiesh,  354 

on  the  stomach,  ib. 

Organic,  in  the  blood,  353 
Passage  of,  through  th«  lungs, 
352 
Salt-works,  loss  in,  79 
Sand,  disintegrates  when  exposed 
to  the  action  of  carbonic  acid, 
87 
Saturation,  capacity  of,  66 
Sausages,  poisonous,  364 
SAU88URE,  his  experiments  on  air, 
15 
On  the  mineral  ingredients  of 
plants,  64,  242-248 
SciBNCK  not  opposed  to  practice, 

124 
SxA> WATER,  analysis  of,  79 


Sea-water — eontintted. 

Contains  carbon,  80 

Contains  ammonia,  80 
Silica,  properties  of,  84,  86 
Silicates,  disintegration  of,  155 
Silver,  salts,  poisonous  effects  of, 
359 

SiNAPIS  ALBA,  387 

Size  of  plants  proportioned  to  or™ 

gans  of  nourishment,  30 
Snow-water,  ammonia  in,  43 
Soda,  may  replace  potash,  70 
Soils,  advantages  of  loosening,  12  # 

Analyses  of,  263 

Exhaustion  of,  113 

Ferruginous,  improved,  95 

FeTtiie,  of  Vesuvius,  131 

Formation  of,  82-92 

From  lava,  131 

Imbibe  ammonia,  51 

Physical  properties  of,  148 

Important,  152 

Exhaustion  of,  1 16 
Stagnant  water,  effect  of,  95 
Stalactites  in  caverns,  93 
Starch,  accumulation  of,  in  plants, 
98 

Composition  of,  37 

Development  of  plants    influ- 
enced by,  99 

Product  of,  the  life  of  plants,  21 

In  willows,  98 
Straw,  analysis  of,  12 

Of  rye,  249 
Struve,  experiments  of,  113 
Substitution  of  bases,  66 
Succinic  acid,  343 
Sugar,  formed  from  acids,  137 

Composition  of,  287 

Carbon  in  sugar,  12 

Contained  in  the  maple  tree,  45 

In  Clerodendron  fragrans,  103 

Development  of  plants,   influ- 
ence on,  99 

Fermentation  of,  287 

In  beet-roots,  45 

Metamorphosis  of,  288 

Product  of,  the  life  of  plants,  21 

Transformation  of,  275,  8eq. 

When  produced,  31 
Sulphate  of  ammonia,  well  adapt 
ed  to  furnish  plants  with  sul 
phur,  61 
Suij>HATX0  in  water  of  ipriogB,  61 


400 


INDEX. 


iSuiiPHATEs — continued. 

Yield  sulphur,  G2 
Sui-PHUR,  crystallized,  dimorphous, 

proportion  of,  to  nitrogen  in 

plants,  62 
Source  of,  in  plants,  58 
Sulphuric  acid,  action  of,  on  soils, 

187 
Sulphurous  acid  arrests  decay,  341 
Sywaptas,  388 


Tables    of    Hessian    and    English 

weigfhts  and  nMasures,  392 
Tannic  acid,  36 
Tartaric  acid,  36 

Converted  into  sugar,  37 

In  wine,  298 
Teltow  parsnip,  30 
Thenard,  his  experiments  on  yeast, 

290 
Tin,  action  on  nitric  acid,  268 
Tobacco  juice,  contains  ammonia,  47 

Nitric  acid,  48 

In  Virginia,  113 
Transformation,  by  heat,  280 

Chemical,  265 

Of  acetic  acid,  280 

Of  carbonic  acid,  106 

Of  meconic  acid,  2S0 

Of  bodies  containing  nitrogen, 
-      282 

Of  bodies  destitute  of  nitrogen, 
280 

Results  of,  31 

Of  wood,  281 

Of  cyanic  acid,  284 

Of  cyanogen,  285 

Of  gluten,  311 
Transplantation,  effect  of,  97 
Trees,  diseases  of,  102 

Require  alkalies,  115 

U. 
Ulmin,  5 
Urea,  converted  into  carbonate  of 

ammonia,  48 
Urine,  contains  nitrogen,  48 

Its  use  as  manure,  47 

Of  men,  173 

Of  horses,  169 

Human,  analysis  of,  173 

Of  cows,  169 


V. 

Vaccination,  its  effect,  382 

Vegetable  albumen,  48 

Mould,  always  contains  carbon- 
ate of  ammonia,  96 

Vegetation,  tropical,  161 

Vesuvius,  fertile  soil  of,  112 

Vines,  juice  of,  yields  ammonia,  46 

Vinous  fermentation,  311 

Virginia,  early  products  of  its  soils, 
114 

Virus,  of  small  pox,  382 
Vaccine,  382 

Vital  principle,  how  balanced  in 
the  blood,  371 

W. 
Water,  carbonic  acid  of,  absorbed, 
17 

Decomposes  rocks,  113 

Composition  of,  36 

Dissolves  mould,  344 

Plants,  their  action  upon,  26 

Rain,  contains  ammonia,  43 

required  by  gypsum,  55 

Salt,  analysis  of,  79 
Waveute,  117 
Wheat,  exhausts,  114 

Gluten  of,  46 

Why  it  does  not  thrive  on  cer- 
tain soils,  115 

In  Virginia,  114 

Red,  143 

White,  182 
Willows,  growth  of,  98 
Wine,  effect  of  gluten  upon,  318 

Fermentation  of,  317 

Properties  of,  318 

Substances  in,  313 

Taste  and  smell,  314 

Varieties  of,  ib. 
WoAD,  decomposition  of,  294 
Wood,  decayed,  combustion  of,  342 

Absorbs  ammonia,  56 

Analysis  of,  24 

Conversion  of,  into  humus,  339 

Decay  of,  338 

Requires  air,  t6. 

Decomposition  of,  266,  295 

Effect  of  moisture  and  air  on,  338 

Elements  of,  339 

Formation  of,  102 

Source  of  its  carbon,  12 

Transformation  of,  981 


INDEX  401 

Wood-coal,  how  produced,  348 

Analysis  of,  348,  349  Y. 

Woody  fibre,  changes  in»  338  Yixbt,  290 

Composition  of,  339  Destro^jred,  313 

Decomposition  of,  338  Experiments  on,  290 

Difference  between  it  and  wood,  Formed,  312 

24  Its  mode  of  action,  293 

Formation  of,  20  Its  production,  338  » 

Moist  evolves  carbonic  acid,  338  Two  kinds  of,  320,  #eg. 

Mould  from,  343 
Wort,  fermentation  of,  319  Z. 

Wounds,  effect  of  putrefying  sab-   Zboutx,  analysis  of,  87 
stances  on,  366 


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